Genny oil

dougrainer wrote:
Synthetic oil is great. BUT, Synthetic oil will go thru minor gaps in various seals that regular oil will not. So, if you have an older engine and have no leaks or just a very minor leak, then start using Synthetic, you will have more leakage. A Mobil engineer told me years ago that it is best to start using Synthetic when the engine is new. NOT a good idea when an engine is used and broken in. Doug

This s another legend on the net (old wives tale) with no proof to back it up.You can switch at any time eather way at any milage.
The only possible problem is if you have excessive sludge the synthetic will clean it out if you have failing seals removing the sludge could open a existing leak path. The same would happen with commercial oil if the sludge was removed.
The only thing that would happen when using it in a older car with hi milage is the rate of wear would be reduced.
Bill