Engine Oil Discussion

[Dale Davies]

I am sorry for bringing this up again but the more I'm reading about it the more I get confused.
I have a high mileage 225 Slant Six which seems to burn and/or loose a bit of oil. I also seems to be never rebuilt. The oil pan is a bit wet but it doesn't seem to be the only issue.
Anyways, I am planning to change the engine oil since the level is low and I don't know what the previous owner had filled in.
In some forums, they said they put in synthetic 10W30 or 10W40 into the Slants while some other say synthetic stuff isn't good, just like what my father said who used to be a mechanic (and ownes some old Volvos) . Some zinc stuff is also required, some people said. My user manual says "no straight mineral oil".
An oil company here in Switzerland makes special oil for old cars. I have found one with extra zinc, based on mineral oil and SAE 50. I now don't know if this will be fine for my Slant... I have read about the Chevron Delo but I would have to import it from the States.


My question now is what oil is not good for the slant, and what do I have to check before I fill in the oil.

My Slant was built in early 1974 with a 3 speed auto, in a 4 door Valiant.

You need between 1500PPM and 2500PPM of ZDDP. That is zinc and phosphorous each. I would be looking at using a 10W 30 oil. A 15W 40 can be used. Shell recommends the Rotella T4 oil for flat tappet old cars. A synthetic could be Amsoil Z-Rod 10W 30. Amsoil has dealers all over, check their web site.
On a mechanically sound engine a synthetic should pose no problems.

 

[Dale Davies]

The "problem" with synthetics is also because it will damage seals/gaskets, right? I've heard synthetics will clean the engine better than conventional oil which causes the engine leaking, because of "missing impurities", which "sealed" the engine, but I don't know what's true about that.
The brand, Motorex (a Swiss brand), produces special oil for old cars. One of those oils has extra zinc, as I've read worn out/not rebuilt engines actually require zinc, so I was thinking about that kind of oil. It is also available in 10W30 or 15W30.

So, a non synthetic oil is "better", but my user manual said i shouldn't add straight mineral oil. This part still confuses me a bit...

Synthetics will not damage seals and gaskets. Early synthetics had two oil base stocks. One is used in AC systems as it works well in the low temperatures. The other works better in hot conditions. Some of the early manufacturers used only one which led to problems.
Amsoil was the first to market with an automotive synthetic oil. Amsoil blends their base stocks to get the desired properties, and then uses a premium additive package.
Now the zinc issue. This is not a matter of high mileage or wworn out engines. It is the flat tappet cams, whether hydraulic or solid. The small high load contact area requires the ZDDP of 1.500PPM to about 2.000PPM to prevent wearing the lobes off the cam.
I have my Ford 289 apart and the cam is showing signs of the cam just at the initial stages of failure due to the lack of ZDDP in the oil. This engine has not been run in 10 years or so. The cause of cam failures was not known for a time to be the removal of the ZDDP. This happened due to catalytic converter incoropration for emissions. A newly rebuilt engine was extremely suseptible to cam wear as the parts wore in and decided to like eachother. The issue was not as evident on older engines that were worn in and spring pressures were not high as a performance built engine would have.
The Shell Rotella T4 oils should be available in Switzerland off the shelf, and be a lower cost option for you. It is a 15W 40 oil, but that should work fine in your slant.
Newer engines use roller followers that work with oils without the ZDDP. Many overhead cam engines use bucket followers with enough load surface to tollerate the lack of the ZDDP. I believe metallurgy plays a big part also. NASCAR when limited to flat tappet cams used DLC coatings to get them to last under the high spring and RPM loads. Expensive process.

 

[Mattax]

You need between 1500PPM and 2500PPM of ZDDP. That is zinc and phosphorous each. I would be looking at using a 10W 30 oil. A 15W 40 can be used. Shell recommends the Rotella T4 oil for flat tappet old cars.

Those concentrations are above the levels ever factory specified and well above the needs of a standard slant six.
See Grant "Oils for Classic British Cars" in a couple places including the motor oil history.
Also Widman's overview of motor oil properties related to flat tappet engines.

Both cite and quote primary sources relating to negative aspects of long term use of zddp above 1500, particularly these two:

“Cam and Lifter Wear as Affected by Engine Oil ZDP Concentration and Type”
Loren G. Pless, John J. Rodgers, Fuel & Lubricants Dept., Research Labs, General Motors Corp. SAE Report 770087, 1977

“How Much ZDP is Enough?” R.M. Olree, (GM Powertrain),M.L. McMillan (GM R&D) SAE Technical Paper Series 2004-01-2986, October 2004

However also note that even as far back as the 1950s, some negative effects of concentrations over 1000 ppm were observed. So its all a balance. If one has an engine with high spring loads, the additive package and oil properties are going to have different priorities than a standard or even a factory high performance engine.

As far as Rotella T4 goes, I would check the recomendation date and compare the T4 specs and VOA from then to currently available product. There were major changes in the additive packages a few years ago.

 

[Rat Bastid]

Those concentrations are above the levels ever factory specified and well above the needs of a standard slant six.
See Grant "Oils for Classic British Cars" in a couple places including the motor oil history.
Also Widman's overview of motor oil properties related to flat tappet engines.

Both cite and quote primary sources relating to negative aspects of long term use of zddp above 1500, particularly these two:

“Cam and Lifter Wear as Affected by Engine Oil ZDP Concentration and Type”
Loren G. Pless, John J. Rodgers, Fuel & Lubricants Dept., Research Labs, General Motors Corp. SAE Report 770087, 1977

“How Much ZDP is Enough?” R.M. Olree, (GM Powertrain),M.L. McMillan (GM R&D) SAE Technical Paper Series 2004-01-2986, October 2004

However also note that even as far back as the 1950s, some negative effects of concentrations over 1000 ppm were observed. So its all a balance. If one has an engine with high spring loads, the additive package and oil properties are going to have different priorities than a standard or even a factory high performance engine.

As far as Rotella T4 goes, I would check the recomendation date and compare the T4 specs and VOA from then to currently available product. There were major changes in the additive packages a few years ago.

THIS^^^^^^EXACTLY.

Phosphated zinc is a necessary evil. It doesn’t play well with other additives in high(er) concentrations.

Adding a bottle of zinc additive to an oil is bad policy. Doing that changes the formulation and it’s most likely not for the best.

Buying an oil that needs an additive means buying a better oil is the correct option.

 

[hotrod swinger]

I’m no expert, but for a 1974 slant six I would just buy the cheapest 10w-30 or 5w-30 available and run it til it dies.

 

[S'cuder]

As far as Rotella T4 goes, I would check the recomendation date and compare the T4 specs and VOA from then to currently available product. There were major changes in the additive packages a few years ago.

That was Shell's recommendation as recently as a few months ago. There are no Shell/Pennzoil/Quaker State automotive oils with high ZDDP additive packages. So, Shell recommends Rotella.
Despite recent reformulation, Rotella still contains a fair amount of ZDDP. But as primarily a diesel oil, it has detergent packages which are far from optimal for our gas engines.
So, even though Shell pays me every month not to work, I'd recommend several alternatives that are better for most of our applications. Mobil 1 FS 0W-20 is at the top of the list.

*Edit* Mobil 1 FS 0W-40, not 0W-20!

 

[Dale Davies]

Those concentrations are above the levels ever factory specified and well above the needs of a standard slant six.
See Grant "Oils for Classic British Cars" in a couple places including the motor oil history.
Also Widman's overview of motor oil properties related to flat tappet engines.

Both cite and quote primary sources relating to negative aspects of long term use of zddp above 1500, particularly these two:

“Cam and Lifter Wear as Affected by Engine Oil ZDP Concentration and Type”
Loren G. Pless, John J. Rodgers, Fuel & Lubricants Dept., Research Labs, General Motors Corp. SAE Report 770087, 1977

“How Much ZDP is Enough?” R.M. Olree, (GM Powertrain),M.L. McMillan (GM R&D) SAE Technical Paper Series 2004-01-2986, October 2004

However also note that even as far back as the 1950s, some negative effects of concentrations over 1000 ppm were observed. So its all a balance. If one has an engine with high spring loads, the additive package and oil properties are going to have different priorities than a standard or even a factory high performance engine.

As far as Rotella T4 goes, I would check the recomendation date and compare the T4 specs and VOA from then to currently available product. There were major changes in the additive packages a few years ago.

I’m no expert, but for a 1974 slant six I would just buy the cheapest 10w-30 or 5w-30 available and run it til it dies.

Carry on. With modern oils that have little to no zinc and phosphous, the cam will fail prematurely eveven with the low spring rates of the slant six. Yes the proper oil.formulation for vintage engines is going come at a bit of a cost, but then what is the cost of an engine overhaul?

 

[Rat Bastid]

Carry on. With modern oils that have little to no zinc and phosphous, the cam will fail prematurely eveven with the low spring rates of the slant six. Yes the proper oil.formulation for vintage engines is going come at a bit of a cost, but then what is the cost of an engine overhaul?

Damn, I’ll say it once more. ALL ENGINE OILS MUST HAVE ZDDP OR THEY ARE NOT ENGINE OILS.

There is no such thing as an engine oil without ZDDP. And ZDDP isn’t just for cam lobes.

These stupid myths need to be stopped.

 

[Dale Davies]

THIS^^^^^^EXACTLY.

Phosphated zinc is a necessary evil. It doesn’t play well with other additives in high(er) concentrations.

Adding a bottle of zinc additive to an oil is bad policy. Doing that changes the formulation and it’s most likely not for the best.

Buying an oil that needs an additive means buying a better oil is the correct option.

Oil formulation is a tricky balance. Putting in an additive might be beneficial or it may put too much in and be harmful.
Your assesment is correct.

 

[Dale Davies]

Those concentrations are above the levels ever factory specified and well above the needs of a standard slant six.
See Grant "Oils for Classic British Cars" in a couple places including the motor oil history.
Also Widman's overview of motor oil properties related to flat tappet engines.

Both cite and quote primary sources relating to negative aspects of long term use of zddp above 1500, particularly these two:

“Cam and Lifter Wear as Affected by Engine Oil ZDP Concentration and Type”
Loren G. Pless, John J. Rodgers, Fuel & Lubricants Dept., Research Labs, General Motors Corp. SAE Report 770087, 1977

“How Much ZDP is Enough?” R.M. Olree, (GM Powertrain),M.L. McMillan (GM R&D) SAE Technical Paper Series 2004-01-2986, October 2004

However also note that even as far back as the 1950s, some negative effects of concentrations over 1000 ppm were observed. So its all a balance. If one has an engine with high spring loads, the additive package and oil properties are going to have different priorities than a standard or even a factory high performance engine.

As far as Rotella T4 goes, I would check the recomendation date and compare the T4 specs and VOA from then to currently available product. There were major changes in the additive packages a few years ago.

The 1,500PPM is what i was reading, definately performance oriented. 2,500PPM was a max level.
The recommendation from Shell technical assistance was when I phoned at most 2 months ago. If I remember he stated the zinc was about 1,200PPM and phosphorous close to the same. The rest of the additive package has diesel oriented components that are not the best for our vintage engines. But they are trying to sell their products and that is the best option they have. Valvoline VR1, Mobil 1 and Amsoil Z Rod along with the Swiss manufactured oil would be the best alternatives for the OP.

 

[RustyRatRod]

Disagreement I’m fine with. Just don’t disagree based on being poor. Or cheap.

I just run the best I can afford and if somebody don't like that, then bump um.

 

[RustyRatRod]

Actually, I'm frugal. It's my wife that calls me cheap.

Maybe so, but you've done more on a bugdet in your life than most people only dream about.

 

[Bewy]

Ask every oil company what their recommended level of Ph & Zn is............& I will bet the answer is different.

Ask the same companies if they have ever tested the concentrations in running engines....& I will the answer is no.

 

[Mattax]

The last time this came up, a check of PQIA test results showed Rotella T4 meeting CK-4 was in the 900 ppm range.
You could see if anything newer is available now.

2020 Analysis of T4 15W-40, API CK-4
Shell Rotella T4 SAE 15W-40 Heavy Duty Diesel Engine Oil | The Petroleum Quality Institute of America

2018 Analysis of T4 15W-40, API CK-4
PETROLEUM QUALITY INSTITUTE OF AMERICA TEST PROGRAM

2016 Analysis of T 15W-40, API CJ-4, CI-4/SM
Shell Rotella T4 SAE 15W-40 Heavy Duty Diesel Engine Oil | The Petroleum Quality Institute of America

From Widman's paper cited above.

Some important points packed into those two paragraphs.

 

[66fs]

I’m no expert, but for a 1974 slant six I would just buy the cheapest 10w-30 or 5w-30 available and run it til it dies.

When I was young, a long time ago, I bought a 64 Dodge that had a Poly 318. It used oil. I tried all kinds of oil at the time, all the big names, and then I tried Valvoline racing 20w50. That engine started burning less oil and eventually only burned less than a quart between changes, at 3,000 miles. I put over 100,000 miles on that car and it was running fine when I sold it to buy the 64 Barracuda. No idea why, I was not into building engines till the 64 Barracuda. I have tried most oils over the years, I remember trying a light weight Mobile 1 when it came out with all their claims. Put it in the 273 and ran it hard. I didn't like the hot idle oil pressure and the way the engine sounded. Drained it right out, after that drive, and went back to Valvoline Racing 20w50. I run Valvoline synthetic 10w30 in the three 5.7 Hemi's we have now. Both the Chrysler and Chevrolet Racing manuals state that straight 30 oil will cause the least wear of any oils. That may dated now. Chrysler Racing also stated that they tested synthetic oil and saw no benefit. As for ZDDP, it is my understanding that the zinc can clog catalytic converters so our "brilliant" leaders have banned it from the latest SAE oil grades. I have no idea what the oil companies have replaced it with. However if your engine does not burn oil, the catalytic converter will not clog? I have a 96 ACR Neon with 250,000 miles on it. I ran either Valvoline Racing straight 30 or 20w50, that have plenty of ZDDP, in it it's whole life. I still have it and it runs like new and has the original catalytic converter. So, I recommend good oil with ZDDP conventional or synthetic for flat tapped cammed engines and change it more often than the recommended intervals with a good filter. I also know you have to do what you need to do, but cars are an expensive item and the cost of good oil is relatively cheap. I won't tell you what good oil is, there are many out there.

 

[famous bob]

When I was young, a long time ago, I bought a 64 Dodge that had a Poly 318. It used oil. I tried all kinds of oil at the time, all the big names, and then I tried Valvoline racing 20w50. That engine started burning less oil and eventually only burned less than a quart between changes, at 3,000 miles. I put over 100,000 miles on that car and it was running fine when I sold it to buy the 64 Barracuda. No idea why, I was not into building engines till the 64 Barracuda. I have tried most oils over the years, I remember trying a light weight Mobile 1 when it came out with all their claims. Put it in the 273 and ran it hard. I didn't like the hot idle oil pressure and the way the engine sounded. Drained it right out, after that drive, and went back to Valvoline Racing 20w50. I run Valvoline synthetic 10w30 in the three 5.7 Hemi's we have now. Both the Chrysler and Chevrolet Racing manuals state that straight 30 oil will cause the least wear of any oils. That may dated now. Chrysler Racing also stated that they tested synthetic oil and saw no benefit. As for ZDDP, it is my understanding that the zinc can clog catalytic converters so our "brilliant" leaders have banned it from the latest SAE oil grades. I have no idea what the oil companies have replaced it with. However if your engine does not burn oil, the catalytic converter will not clog? I have a 96 ACR Neon with 250,000 miles on it. I ran either Valvoline Racing straight 30 or 20w50, that have plenty of ZDDP, in it it's whole life. I still have it and it runs like new and has the original catalytic converter. So, I recommend good oil with ZDDP conventional or synthetic for flat tapped cammed engines and change it more often than the recommended intervals with a good filter. I also know you have to do what you need to do, but cars are an expensive item and the cost of good oil is relatively cheap. I won't tell you what good oil is, there are many out there.

you guys not remember why the factories went to roller cams ??
The gov. put mandates on oils , and took almost all the zink out of oils .

 

[j par]

Goodness sake... oil and spark plug threads seem to have endless opinions...
As usual it'll likely finally end in personal attacks...
Change your oil and spark plugs and enjoy your car...

 

[RustyRatRod]

Goodness sake... oil and spark plug threads seem to have endless opinions...
As usual it'll likely finally end in personal attacks...
Change your oil and spark plugs and enjoy your car...

Yeah, engines are probably happier with spark plugs and oil in them. Anything more than that is a personal decision. LOL

 

[j par]

Yeah, engines are probably happier with spark plugs and oil in them. Anything more than that is a personal decision. LOL

We could start telling each other to f off and personally attacking each other and help this thread along LOL...

 

[RustyRatRod]

We could start telling each other to f off and personally attacking each other and help this thread along LOL...
View attachment 1716101115

Naw I think it has all the help it needs. lol

 

[j par]

Naw I think it has all the help it needs. lol

Well crap we haven't tangled in a while...

 

[RustyRatRod]

Well crap we haven't tangled in a while...

I don't really want to. I like you too much for all that chit. You're one of my favorite people on here. ...now don't let that go to your head.

 

[j par]

I don't really want to. I like you too much for all that chit. You're one of my favorite people on here. ...now don't let that go to your head.

Well if you think a comment like that's going to humble me and get me to shut up... Well d*** you anyways you were right...

 

[Rat Bastid]

When I was young, a long time ago, I bought a 64 Dodge that had a Poly 318. It used oil. I tried all kinds of oil at the time, all the big names, and then I tried Valvoline racing 20w50. That engine started burning less oil and eventually only burned less than a quart between changes, at 3,000 miles. I put over 100,000 miles on that car and it was running fine when I sold it to buy the 64 Barracuda. No idea why, I was not into building engines till the 64 Barracuda. I have tried most oils over the years, I remember trying a light weight Mobile 1 when it came out with all their claims. Put it in the 273 and ran it hard. I didn't like the hot idle oil pressure and the way the engine sounded. Drained it right out, after that drive, and went back to Valvoline Racing 20w50. I run Valvoline synthetic 10w30 in the three 5.7 Hemi's we have now. Both the Chrysler and Chevrolet Racing manuals state that straight 30 oil will cause the least wear of any oils. That may dated now. Chrysler Racing also stated that they tested synthetic oil and saw no benefit. As for ZDDP, it is my understanding that the zinc can clog catalytic converters so our "brilliant" leaders have banned it from the latest SAE oil grades. I have no idea what the oil companies have replaced it with. However if your engine does not burn oil, the catalytic converter will not clog? I have a 96 ACR Neon with 250,000 miles on it. I ran either Valvoline Racing straight 30 or 20w50, that have plenty of ZDDP, in it it's whole life. I still have it and it runs like new and has the original catalytic converter. So, I recommend good oil with ZDDP conventional or synthetic for flat tapped cammed engines and change it more often than the recommended intervals with a good filter. I also know you have to do what you need to do, but cars are an expensive item and the cost of good oil is relatively cheap. I won't tell you what good oil is, there are many out there.

Let’s see if I can do this without offending you.

1. There is never, ever a reason to run a single grade oil. Ever. The Viscosity Index Improvers since the late 1970’s have been improved. So has the base oil.

Any engine oil that is multi-grade (there is no such thing as oil “weight”) starts out its life as the lower grade. A 20w50 starts out as a 20 grade oil and VI improver are added (among other things) so that the oil acts like it’s higher grade at 212 degrees.

Thats why you never saw a 0 grade oil until not that long ago. The VI improves and base oils weren’t good enough to start with that grade of oil.

At one time Castrol made a 10w50. I used to use it. They stopped making it around 1984ish (IIRC) because the bad oil wasn’t capable enough and the VI improvers had issues with that range.

Today, with a QUALITY synthetic oil (that means Group IV and V base oils ONLY) and todays VI improvers you can get a 5w50 and it will outperform ANY single grade or 20w50 in every single test there is.

You can also run a 0 grade base oil (I run either a 5w30 or probably will run a 0w20 this time) which means you can close up the clearances, carry the same oil pressure and get better cooling and protection than you can with a heavier grade oil. You couldn’t do that in the 1970’s. Or the 1980’s.

The “synthetic“ oils Chrysler was testing are not the same oils we can buy today. So that testing is obsolete. So is the advice that single grade oils offer more protection than multi grade oils. They don’t.

The government didn’t “ban” zincdiakyldithiophosphate (ZDDP). As I said above, ALL ENGINE OILS HAVE ZDDP OR THEY ARENT ENGINE OILS. The government mandated lower levels of ZDDP because no matter how good with a bone you are, no matter how good your rings are, there is oil migration out the exhaust. The ZDDP coats the catalyst and kills it.

ZDDP isn‘t just for cams. It’s for the rings, the exhaust valve guide and any other extremely hot, high load parts.

So there is no “BAN” on ZDDP.

There are many middle of the road, will work well enough oils out there. There are very few high quality oils out there. And you don’t find them at box stores and crap holes like Walmart.

 

[66fs]

Let’s see if I can do this without offending you.

1. There is never, ever a reason to run a single grade oil. Ever. The Viscosity Index Improvers since the late 1970’s have been improved. So has the base oil.

Any engine oil that is multi-grade (there is no such thing as oil “weight”) starts out its life as the lower grade. A 20w50 starts out as a 20 grade oil and VI improver are added (among other things) so that the oil acts like it’s higher grade at 212 degrees.

Thats why you never saw a 0 grade oil until not that long ago. The VI improves and base oils weren’t good enough to start with that grade of oil.

At one time Castrol made a 10w50. I used to use it. They stopped making it around 1984ish (IIRC) because the bad oil wasn’t capable enough and the VI improvers had issues with that range.

Today, with a QUALITY synthetic oil (that means Group IV and V base oils ONLY) and todays VI improvers you can get a 5w50 and it will outperform ANY single grade or 20w50 in every single test there is.

You can also run a 0 grade base oil (I run either a 5w30 or probably will run a 0w20 this time) which means you can close up the clearances, carry the same oil pressure and get better cooling and protection than you can with a heavier grade oil. You couldn’t do that in the 1970’s. Or the 1980’s.

The “synthetic“ oils Chrysler was testing are not the same oils we can buy today. So that testing is obsolete. So is the advice that single grade oils offer more protection than multi grade oils. They don’t.

The government didn’t “ban” zincdiakyldithiophosphate (ZDDP). As I said above, ALL ENGINE OILS HAVE ZDDP OR THEY ARENT ENGINE OILS. The government mandated lower levels of ZDDP because no matter how good with a bone you are, no matter how good your rings are, there is oil migration out the exhaust. The ZDDP coats the catalyst and kills it.

ZDDP isn‘t just for cams. It’s for the rings, the exhaust valve guide and any other extremely hot, high load parts.

So there is no “BAN” on ZDDP.

There are many middle of the road, will work well enough oils out there. There are very few high quality oils out there. And you don’t find them at box stores and crap holes like Walmart.

Never offended by respectful conversation. A lot of oil choice comes down to personal preference and experience. Not sure what tests you are referring to, I have trust issues. Good to get the scoop on ZDDP, I might not have had it perfect, but in practice, I was on target. In reality I don't shop at Walmart.