what oil is safe?

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7duster4

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What does everyone here use for oil? I have been told by many people that todays oil is bad on engines with flat-tappet cams. Due to the lack of zinc. Since my 318 was rebuilt I have been using mostly Valvoline. One friend of mine said he uses one quart of Shell 15w-40 Rotella with every four quarts of conventional oil. Another friend of mine said to use one quart of mobile one synthetic with four quarts of conventional oil. What do you guys use in your muscle cars? I have put over 1,000 miles on my car since the rebuild. I don't want to ruin the engine just becuase of the oil. Any help is appreciated. Thanks
 
I used Castrol GTX 5W-30 on my last change, and added to that a bottle of STP Oil Additive. It's a thick goopy syrup that is basically the ZDDP stuff that we need. Use any oil you like, then add that STP stuff.
 
Run 15w-50 mobil1 here. Has about the same additives as diesel oil, but with the 3.91s and the occasional highway run, ill sleep better with the better oil,
 
I used to run kendall gt-1 10w40 in my 340 I was told bty machinist to run full pan of rotella 15w40. No problems ,and have found many guys running the same even in race engines Steve
 
Look under forums for mopar performance issues,find the thread on what oil to use,and you have about 9 pages to read.
 
Thanks guys I will keep those in mind when I do the next oil change. I'll be sure to look up this topic in the performance section.
 
I run Mobil 1 synthetic in our mazda and will run it in my valiant when it's done. It's a great oil for cold starts, we also use it at work in the turbine's and gear boxes. Ok not mobil1 but another mobil product called mobil jet 254, we have switch over to this from shell brand. It's a much better oil.
 
I have a friend who works at Exxon/Mobil in the lubricates area (basically a mechanical engineer who specializes in industrial lubrication).

Anyway he looked up all of the ZDDP values for the MOBIL 1 product line and informed me that the two Mobil 1 versions of 15W50 oil (extended life and ?) both have around 1200 ppm of ZDDP. The Motorcycle oils have even more, but cost like $8-9 a quart. The remaining Mobil 1 product line are all SM products so they have lowered the ZDDP content of the oils, like everyone else in the industry.

I plan on switching my engine over to the 15W50 Mobil 1 , but I am still looking for a local source for it in gallon containers.


I believe if you do the math you will find that one small container if STP will not raise the ZDDP levels in 5 quarts of SM oil to the levels needed for a HP flat tappet camshaft
 
If you read any SAE technical articles by either the oil manufacturers or car manufacturers SM rated oil is more than adequate for engines with stock or close to stock cams and springs. It's when you start going to real radical lift cams with high spring pressures that the 800 ppm of ZDDP in an SM rated oil starts to be marginal.

Those articles will also say it's a good idea to use a supplement with any flat tappet cam during break in.

Diesel oil is not necessarily any better. you have to look at the ratings on the bottle. Diesel oil with a CJ rating has reduced levels of ZDDP as does SM rated gasoline engine oil. Any oil with the highest rating of SL or CI should be good, being synthetic is not the answer either, it's still the serive rating that defines how much of the ZDDP that is necessary to protect a flat tappet cam.

I have always used Mobil 1 oil in my turbo cars because of it's higher temperature ratings and also use it in the Barracuda that has a flat tappet cam because it is more resistant to the formation of acids and it allows me to do one oil change per year. Since the whole issue of ZDDP levels in oil became a hot topic i started putting in a bottle of STP with each oil change in the Barracuda. Anyway, 20k miles and counting on the Comp XE268H cam.
 
as of janurary 2007 desiel fuels and oils have changed,, goverment mandated to lower sulfur in desiel fuel,,like they have years ago in other countries,, the zinc in the diesel oil effects the partitulate matter in the exhaust,, so all desiel oil even shell rotella T has lowered theree zinc ( zddp ) content in diesel oil,,,,, the zinc in auto oil for muscle car and racing is still a matter no one really knows the truth,, since syntheic oils im told will find or make a engine more pron to leak oil,,, ?? ( any one having this problem ) ?? i am going to use what i have all along sae 30 wt, and use comp cams additive,, i recently broke in a set of lifters in an early hemi in my street rod with normal oil and comp cams additive,,,seems to work fine,, i get the additive at my local speed shop,,across the street from my house,,
 
What I have heard and learned about synthetic oils is that it may not be compatible with all seal/rubber compounds. I would suggest that if you are looking at building an engine look for the seals that will work with synthetic oils. I will look through some of my old school text books to try and find out what works.

After some cold starts in Dawson Creek -40 and colder, with the block heater not working, I was more that sold on the synthetic oils.
 
Synthetic oils not being compatable with seals is an old wives tail. They wouldn't be able to carry an API service rating if that was the case.
 
In my stroker which sees lots of high rpms and track time i run Shell rotella 15-40 with a half qt. of Lucas oil treatment,i've had no issues with anything since putting the stroker in 3 years ago,then again i change the oil every 25 passes...
 
Well I'm not sure about seals being competable with sysnthetic oils though I have to back to what I was tought in school. What the text books state is that synthetics may cause rubber seals to swell, now this is also a text book for Aircraft Maintenance and the oils may be a little different.
 
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