I have heard of all the benefits of synthetic oil, but have also heard that it's
>best not to run it in an older engine that has been using dino oil, as the seals
>and o-rings may start to leak and cause a bigger problem than they solve. >
>So my question is, how old is too old? I have a '92 Buick with a 3800 under the
>hood. It's old, but only has 68,000 miles on it, barely broken in for a 3800.
>Would I get any benefit from synthetic? How about (more importantly) any likely
>drawbacks?
>
>Thanks,
>
>Mike O'Malley
>
I've switched vehicles that had 150K on them to synthetic with zero problems. Occasionally you'll get leaks from gaskets/seals that were gunked up after the synthetic cleans out the gunk.
The only real problem I've had with synthetics was when I sucked the old dirty icky power steering fluid out of a Mustang and replaced it with Valvoine Synthetic PS fluid. The rack started leaking badly shortly thereafter. Switching back to regular PS fluid slowed it down but I had to replace the rack a few months later.