High mileage oil?

[havic]

Does high mileage oil make a difference? I have 87,000 miles on my 98 and I've seen some high mileage oil on the market that says for vehicles over 75,000 miles. Would it be beneficial to use that oil? And once you use that oil, is it one of those things that you have to continue using (ex. would it hurt the engine to switch back to regular oil)? Thanks.

[Brian R.]

The way I understand it, high-mileage oil is supposed to help in sealing marginal gaskets and seals by swelling them with some additive.

IF (big if) they actually do this, going back to using a standard type oil would eventually shrink those seals back to their original density. Since the swollen seals will wear at their larger size, shrinking them back will probably cause additional leaking.

There may be additional properties to these oils I'm not aware of. They may have no properties other than those of standard oils. Some may work and some may not.

My opinion - don't switch unless you are having oil leak issues, and if you do, don't expect much and don't go back to standard type oils unless you don't run the high-mileage oil very long.

[havic]

Seems like it's better to stick with regular oil then, because it would just be prolonging the inevitable, which is replacing your seals if you have an oil leak.

[Brian R.]

Well, using the high-mileage oil may turn your leaker into a non-leaker and give you another 50k beyond what you would have put up with in leaks.