I am a firm beliver in synthoil and I recently bought a used car for winter/snow days. It has 70K miles on it and I have to assume its running on petroil. I want to know if I can I change it over to synthoil? A lot of sites say that I can’t because it breaks up the sludge and that would mess up the rings, or cause a clog in the oil system.
If I do switch over, what should I do to prep the oil system? I’ve heard to put in a good oil cleansing additive (to prep the sludge I guess) and my grandfather always swore by Rislone. Should I be ready to have the rings replaced if they do leak after the changeover to synthoil?
if your engine has any “sludge” in it, you’ve got bigger things to worry about than your type of motor oil.
that said, I’m not aware of synthetic oil inherently having any higher level of detergents than conventional. I’m also not convinced of synthetic having any great benefits at all; the “stability” and life of motor oil depends far more on the additive package than the base oil. I’ve got one car (turbocharged, even) with 144,000 miles on it, and it’s only ever had conventional oil. as of a couple months ago, it still has spec compression, oil pressure, and doesn’t use any measurable quantity between changes.
I can’t emphasize this enough. Motor oils are engineered fluids and engines themselves are engineered for the specific properties of specific grades/ratings of motor oil. Dumping random additives into your oil (and especially your automatic trans fluid) is the height of stupidity.
Er, you don’t just “have the rings replaced.” If the piston rings are toast, you are in need of an entire engine rebuild. The cylinders have to be machined true and refinished because the (new) rings need a specific surface finish to seat in and seal properly.
Way back when (1940’s?) with the introduction of high-detergent motor oil, many vehicles were switched over to using it. Unfortunately, a noticeable number of these vehicles suffered engine damage from the detergent additives loosening accumulated sludge and sending it through the engine. From this arose the warning to not change types of oil, which unfortunately has persisted through the years and been (wrongly) expanded to include brands and viscosities. And now it seems to have (wrongly) expanded further to include changing from conventional oil to synthetic.
I agree with Philster [ETA: and jz78817]. I know of no harm in changing to synthetic oil. I do know of harm from using aftermarket additives and from “engine oil flushes.” Flushing has the dual risk of possibly liberating depositied sludge and of replacing nice lubricating oil with not-so-lubricating solvent.
Here’s a site that I 95+% agree with. It has a lot of good info.
Mainly I don’t see much point in stressing oil analysis. It’s fine for gearheads who get into that sort of thing, but I don’t think the average Joe or Jane is particularly interested in sending samples to a lab and wading through all the technical details in the report. And I don’t think they need that. The great majority of folks can follow the manufacturer’s schedule, as he recommends, and do just fine.
To some, it is old.
He really called it* used* in the thread and I think he wants to use synthetic in his vehicle be it new or used. Just an issue about switching, not which is best for something old.
In the title, he does call it old, but that is just relative to some.
.