Will a syn blend cause the problems a full syn will on an old conv only engine?

[4WD]

Folks have been using synthetic oil for several decades.
Think how many vehicle and formula combinations that is …

 

[tolian21]

Replace seals if they are bad? Really? On the old car that is at its end of life, the last thing you want is to spend $$$ on it. Who cares if synthetic oil does not cause leaks, maybe he just want to get another 6 month out of it, why does he need new kind of oil now that can clean sludge and expose bad seals?

 

[tolian21]

Synthetic may easily *expose* them due to the properties of an ultra- refined oil once it clears the residue left by years of conventional oil.

Exactly my point. At the end of life, when your car is worthless and all you need is a bit more time before you toss it — its not a good idea change anything that was done for 20 years. When it cost you money, there is little comfort in knowing its not synthetic that is at fault

 

[addyguy]

Try a high-mileage oil

 

[Alex38]

I’d be running a High-Mileage oil if that were my car. Most, like Valvoline MaxLife, are blends anyway. The HM oils may help reduce the chances of a leak after switching oils.