OIL?

[Z282SLO]

Can you just run synthetic? What if regular oil was run in the car since new?

The motor's probably shot and you should sell the car as fast as possible.

Kidding aside, you can switch to synthetic w/o a problem.

How many miles do you guys go before changing synthetic?

I change my oil once per year regardless of the miles I put on the car. Although I don't put on the kind of miles where I would need to change the oil sooner.

[bdecoy]

Ya I put moble one in 1521 now. 2946 has Castro 20-50 synthetic

[vinchez78]

Change oil Every 5000 miles

[JohnLynch]

Few more questions;

Is it bad for a motor to have been on synthetic then back to regular oil?

Also our cars original oil was FMC 5w-30 correct?

Thanks

[jstanley55]

Is it bad for a motor to have been on synthetic then back to regular oil?

I've heard rumors that when going from synthetic to regular new oil leaks may appear. With that said I don't remember the reasoning behind it.

[psucobra]

I'll be running Amsoil 5W-30 Signature Series with a Ford FL1A filter.

[Z282SLO]

Also our cars original oil was FMC 5w-30 correct?

Thanks

FMC 10W-30

[Z282SLO]

Is it bad for a motor to have been on synthetic then back to regular oil?

I've heard rumors that when going from synthetic to regular new oil leaks may appear. With that said I don't remember the reasoning behind it.

Never heard that. I switched from regular oil to synthetic and then back again in my '89 GT over the years w/o any issues.

[JohnLynch]

Is it bad for a motor to have been on synthetic then back to regular oil?

I've heard rumors that when going from synthetic to regular new oil leaks may appear. With that said I don't remember the reasoning behind it.

J, I have heard that too just wasn't sure if it was an urban legend so to speak

[93N8]

I've always heard if you switch from reg to syn that the detergents in the syn could cause leaks. Especially on higher mileaged vehicles

[Z282SLO]

Based on what I've been able to find, those leak worries with synthetics may have been true years ago but no longer.

Here's an excerpt from a Popular Mechanics article from 2007 -

"Early synthetics got a bad reputation for leaking. This was because, despite the claims of the oil manufacturers, the seal-swell characteristics of the new synthetics were different from those of the mineral oils they replaced. If the seal-swell rate was lower, the seals shrank and oil leaked from crankshaft seals and rocker cover seals. If the rate was higher, the seals swelled a little extra and the engine was tight. Then if the owner changed back to mineral oil, or added a quart when no synthetic was to be had, things got really bad. The crank seals had become worn, in their turgid state, and then relaxed. The valve cover seals were compressed when swelled, and when the different oil was added, everything leaked like, well, an old English sports car.

Fortunately, the situation has improved; you should have no problem switching back and forth. Adding a quart of mineral oil to a crankcase full of synthetic will be fine. Read the fine print -- a lot of the "synthetics" on the market are blends containing a substantial proportion of mineral oil."

It's a safe bet that synthetic oil and synthetic blends are just as good if not better today than they were when this article was written in 2007. Like I said above, I switched back and forth in my '89 with no problems.