Is using synthetic oil on a high mileage car a good idea?

[BillyRay59]

Need to change the oil on my 97 Z28. It has 99k miles. The Chilton's manual says not to use synthetic oil on high mileage cars because it is thin and will blow by the rings? Any thoughts/experiences? Thanks!

[lf93formula]

I've heard this before but I don't really agree with it. Being "thin" means it has a lower viscosity and viscosity is measure by the weight. A 5W-30 should have the same viscosity whether synthetic or not. That said, Synthetics do have better lubricity and are less susceptible to thermal break down. If you have a high mileage engine you can chose an oil for high mileage be it synthetic or conventional.

[mikewoods]

Check out www.bobistheoilguy.com.

[nascarnate326]

Id say stay with what you have.

Change oil and get a leak....that would be crappy.

[BP_Z28]

Just use a high mileage oil. It has a sythentic blend. Run it in the cobalt,and camaro with no problems

Sent from my DROID4 using Tapatalk 2

[TrickyTransAm]

I switched my 90 bonneville to full Mobil 1 Synthetic at 200K miles and I didn't have these issues.

Every vehicle is different, but IMHO you want to run synthetic in an older vehicle just because it is supposed to stop any further excessive wear.
I know in my vehicles, it quieted everything down, and it ran better all around.
Started better in winter too.

It could also be said that they installed it too early to a low mileage engine, where the components didn't get a chance to seat and wear in properly.

[SOPES]

I just have seen leaks caused by the synthetic. Id go for the high mileage stuff as well.

[Lewis48661]

Not to hijack the thread but I'm kinda in the same boat only my 1996 z26 has 147000. Previous owner had just had the oil changed before I got it. Thing is now that I'm thinking its time to do it again I'm not sure if syn or standard oil was used. I also have a couple drops leaking from the front of the motor so I sure don't need that getting any worse. Any suggestions would be great help.
Also should I stick to the factory 5w-30 or maybe go to 10w-30? Again not sure what's in it now.

[SOPES]

Id stick with the factory 5w-30, just use the high mileage stuff. Lucas oil makes a bottle of oil stabalizer and I usually put some in when I change my oil. It just sticks to parts better so its less wear when you start up if your cars been sitting a while

[SSTODD]

Try this if you are able. auto rx.com

it will clean all the internals and repair seals safely using regular oil for cleaning and rinse phases, very good stuff that works.

I used it in both 120k mile Grand Prixs I have, then you run whatever oil you want once the insides are clean.

[formula218]

I run Rotella T6 in my LT1 with no issues. I've ran in in my last 3 modded cars and its been fine. It's cheap for a synthetic and designed for diesel trucks. I always let it warm up for about 5 min before I drive it and make sure the oil pressure is up. I never drive it when it's below 60° so it's never too thick.

[81DaytonaPaceCar]

Id stick with the factory 5w-30, just use the high mileage stuff. Lucas oil makes a bottle of oil stabalizer and I usually put some in when I change my oil. It just sticks to parts better so its less wear when you start up if your cars been sitting a while

^^^ This.

Also, most of the zinc has been removed from oils these days, and Lucas puts zinc back into the system...

Really only critical if you have a flat tappet cam, but still worth noting...

[Lewis48661]

Thanks for all the info guys

[landstuhltaylor]

I run Rotella T6 in my LT1 with no issues. I've ran in in my last 3 modded cars and its been fine. It's cheap for a synthetic and designed for diesel trucks. I always let it warm up for about 5 min before I drive it and make sure the oil pressure is up. I never drive it when it's below 60° so it's never too thick.

I used that once in my VW and it's going into the bike next. That stuff is great and incredibly cheap.

[SOPES]

The other benefit of the lucas stuff is it slows leaks, doesnt stop them so it doesnt swell the seals but is just thick at all times to block oil leakage