Hey, can you run synthetic on a car that always runs normal oil? someone told me that it can fry you valve seals or something like that ? By the way this question is aimed at my 86 2.8 Fiero and a 95 neon.

Sticking synthetic in your Fiero is no big deal - but it MIGHT leak afterwards if some of your seals were "on the edge of leaking" anyhow.

Synth just doesn't make the seals swell up as much as dino oil, and it doesn't carry the crud around. If it leaks, just switch back and after a change or tow the gunk will plug things back up again.

switched to mobile one at 70,000. ran for years to 220,000. sold car still running great. beat hard 4 banger cavalier. switch!

when synthetic oil was just coming out there was stuff that would tend to crack the seals and such, nothing to worry about now.

I dont know about switching back to regular. supposedly its bad for the engine to do that. not sure why but heard that from countless people and techs

------------------

+ an 88 Caprice 9C1 Police Package
--Adam--
IM AOL: FieroGT5speed

synthetic is the best way to go. as far as leaking oil, do not worry about this, they have added the chemical that swell's the seals just like regular oil. I think you will notice a difference in the way your engine runs. I prefer mobil 1.
don

A little side note... a few years ago oil manufacturers sued for the right to use synthetic on oils that are not fully synthetics and often now don't even meet the same standards some conventional oils meet. Mobil1 works and as some others have said, they have been reformulated to keep seals working so the only issue with switching is that they clean rings out real good and engine may burn more oil if the carbon buildup was sealing the rings

Also of interest, some car manufacturers have technical service bulletins to run 0w20 (no I didn't miss a 1) Mobil1 oil in cars that the valvetrain is ticking from running to long between oil changes. I had this help save a customer's Rodeo where she just stop showing up for oil changes for about 2 years for some reason. Car burned oil after that for about 2 oil changes and then was fine again.

I've had good luck with Castrol Syntec full synthetic (one of the not really full synthetics actually) but stay away from the ones advertised as blends. They generally contain 5-10% synthetic... not anywhere near half like you would think, it's a pure advertising gimmick. It would be cheaper to run half cheap oil and half Mobil1... and probably more effective, but I'd just run the Mobil1 and the best oil filter you can get (not a fram). I run full synthetic in my 86 New Yorker with a 2.2 turbo since I got it ( with over 100K on it) and modified the alternator a wee bit so I had enough clearance to run a Motorcraft FL1A filter in place of the tiny little mopar filter. I'm closing in on 200K with no oil issues and the original turbo still boosts nice with no seal issues.

Hope this helps.

Here's some other discussion on the subject:

https://www.fiero.nl/forum/Forum2/HTML/055214.html