JohnLynch wrote: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.
JohnLynch wrote: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.
03 COBRA Black with VMP
93 COBRA Black #3754 (RIP)
89 GT Black/Scarlet Red (SOLD)
86 GT Bright Red/Gray (SOLD)
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.
03 COBRA Black with VMP
93 COBRA Black #3754 (RIP)
89 GT Black/Scarlet Red (SOLD)
86 GT Bright Red/Gray (SOLD)