Synthetic In High Mile Engine?

[MOPARJ]

This may be a stupid question, but would it be safe to put Mobil 1 15w-50 synthetic in my 82,000 mile 318 with a Comp 260 cam that has 2,000 miles since installation? The only oil leak i have is a few small dribbles from the rear main immediately after it ran for a while, but thats it and it stops too. Thanks.

 

[340mopar]

If it doesn't use oil which would make it expensive and pointless to use a synthetic oil absolutely you can put synthetic oil in it. I run synthetic all all my rigs. I have '92 Dodge B350 van with 205,000 and run synthetic in it. Wifes car has 135,000 my driver has 154,000.

Chuck

 

[71valiant]

The one thing you need to know about syntheics, especially Mobil 1, It will seek out spots and possibly leak. I run Mobil 1 full syntheic in my SRT-4 and love it. But it is prone to finding it's way out.

 

[Ace]

82k isn't exactly high mileage, so if the motor's in good shape (not sludged, burning oil or similar) I'd go right ahead. I think the 15w50 is a bit on the heavy side, tho.

On a high miler, or engine with an unknown service history or possibly suspect due to noise, smoke, whatever, I'd run an Arx treatment or flush to try and clean it up first:

http://www.auto-rx.com/

I don't recommend the solvent-type quick flushes. AutoRx is best, but pricey.

 

[lawndart360]

As a hobbyist, I have done quite a bit of homework on the entire synthetic/non-synthetic argument. A couple of things to understand is that the molecular structure of synthetic oil, is tiny, little, uniform balls. The molecular structure of crude based oils consist of squares, diamonds, triangles, etc, thus the synthetic molecules are much smaller, leading to their ability to leak were others do not. Having said that, the tiny structure also lends well to better lubrication, reportedly anyways.
As far as viscosity, I think your choice unless specifically needed is a little heavy. I used Mobile 1 in both my daily drivers and have for years. I still insist on regular changes, even though the oil may not necessarily be breaking down, it still gets dirty and there is only so much and for so long that filters can last.
The debate between the two could go on forever with rock-solid arguemtns for either side, the choice is yours.

 

[340mopar]

The molecules of air are smaller than the molecules in the oil. If the gaskets and seals are air tight in your motor, which they should be, you won't have any leakage difference from one oil to the other. The only advantage to petrolem based oils are they are cheap, this would be the only advantage. If you want the best of both worlds use a synthetic blend, they are reasonably priced and still have some of the synthetics desirable properties against breakdown and anti wear. If you count the longer mileage you can achieve between oil changes the synthetics become more inexpensive to use. The company I purchase my sythetic oil from do oil analysis for me at oil changes and from that, get recommendations on change intervals. On a '96 Bronco I had it went up to 10,000 miles between changes. If you do the math of purchasing synthetic oil & filter once every 10,000 miles and purchasing petroleum based oil and filter 3 times in 10,000 miles I am money ahead, so the low priced advantage is now gone. This Bronco had 178,000 miles on it when I sold it and was down only one quart at oil change (10,000 miles). The trans, transfer case and diffs also had synthetics in them and they were the original.


Chuck

 

[rumblefish360]

In the wifes car, since it doesn't leak, I run sythn oil. Only a 130,000 miles.

Crude in the Magnum since it does burn it up a bit. Unknown miles.

Crude in the Duster for now. This engine came from the Magnum. I have documents with over 300,000 miles when the orginal stopped writing it down in 1989 when he gave the car to his Daughter for 4 years of collage in upstate N.Y. (I live down state.) and then to his son for the same reason, 4 years as well. He then used it for a daily driver to work 50 miles away for 5 years when I got it. I just flipped the odmeter again.
I only changed out cam bearings with the new cam. Otherwise, no major repairs.

If it dosen't leak after some time, I'll go to synth.