I just had my oil changed this afternoon and I have always used valvoline durablend. My new mechanic (moved to a different state) told me the only thing he would change about my service was the oil because Valvoline and Pennsoil have a lot of wax in them and can cause the motors to get "gunky." I have not heard this and my last mechanic said the oil and engine have been very clean. Is there really wax in these oils?

When the Pennsylvania oil fields were producing(not anymore), there was supposedly a paraffin content in that oil. I suspect he's confusing paraffin with wax.

It's an outdated story.

Use any name brand oil and change it every 3K.

There have been a lot of horror stories posted about Pennzoil, but I don't buy it. Too many people use it. If there have been more failures using Pennzoil it's simply because it's the leading selling motor oil which gives it more opportunity to be overlooked by people who don't take care of their cars.

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'91 300-SEL

No. Pennsylvania-grade crude oil is parifin-based, but Penzoil and Quaker State no longer use Pa crude. Not that Pa crude was any better or worse than asphalt-based crude. Both will gunk up a motor if not changed regularly.

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1989 300 SEL that mostly works, but needs TLC