Hi all,
Here comes a question that does not mean to stirr the pot. A lack of knowledge always provides excessive writing inspiration for me. Statement 1: None of the motor oils (neither dino nor synthetics contain any silicone additives). Statement 2: Engine seals get tired with time: contact with high temeperatue oil hardens the rubber. Statement 3: It is a good idea to use an oil "stop-a-leak" additive containing silicone for high mileage engines. Those additives would not hurt anything and would sooth, restore the rubber seals. I understand that modern motor oils are extremely sophisticated , well balanced mixtures. Mobil 1 15-50 (fully synthethic), that I just switched to, states that it features the "... SuperSyn anti-wear system... which helps extend engine life by reducing wear and oil breakdown". That probably translates into better lubricating abilities. How about those "rejuvenating effects"?
Thx.

I have been surprised to find that my older diesels do fine with synthetic (Rotella 5w40). I wouldn't choose to use it due to price except for the harsh Michigan winters. They don't use any more synthetic than they do dino.

I would add though that I've purchased all my vehicles with the number one priority being.....that they don't use oil. This tells me about the maintainence history of the other areas of the car.

Don

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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

I recently posted a quote from a Mobil technical guy who talked about using Mobil 1 in old cars. The gist of it was that if the engine is still in good enough shape that it won't leak or burn much oil the engine should benefit from synthetic. If you try it and don't like it there will be no damage done, just go back to dino. Do a search if you are interested in the exact quote.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold