Date: Mon, 14 Jun 1999 14:06:59 GMT From: "Robert L. Davis" <iclicknopsam.com> Subject: Re: Engine Oil
> I've been sort of following the synthetic oil conversation and I'm not an > engineer. It seem of what I have been reading about different oils that > most praise using synthetic oils. What I find confusing is what kind of oil > changing schedule does one keep. I have heard 15000 miles between changes! > When do most of you synthetic oil user change your oils., 7500, 3000 or > 1500? Jay Royal Purple recommends 10-12k mile changes with a filter change every 5k. I change the oil and filter in all my vehicles at 5k intervals, but the RP engineers I've talked to say that is very conservative. I'm of the old school where oil changes are traditionally done at 2500- or 3000-mile intervals, so even this 5000-mile schedule makes me a bit nervous, but have stuck with it for several years with no problems. I am comfortable with it now. Saab recommends 10k intervals and doesn't even specify synthetic oil, but I think that's too long for fossil oil. You could get by with that with a good synthetic, I am sure, but I wouldn't try it with a run-of-the-mill fossil oil, especially in a turbo car. As for the wisedom of using synthetic oil, ponder this: Generally speaking, synthetic oil has better cold flow characteristics, oxidizes less and holds viscosity better at high temperatures, has better solvency, among many other advantages. Now, how much is this costing you? If you buy five quarts of Castrol GTX, a very good fossil oil, you'll be paying maybe $10 including a filter. For Mobile 1, for example, you'll be paying about $23 for the same oil change. Now, how often do you change it? Every three months? Six months? I don't think anyone will say that fossil oil is as good as synthetic in any category except price, so why not just use the best for the extra 10 or $15 more you're paying for a synthetic, knowing you're using what's best for your car? What's that costing you, maybe $20, $30 per year assuming you're changing the oil at the same interval? While I would change a fossil oil every 3k miles, you can do 5k at least with a synthetic, so now the figures are falling about even. OTOH, if you're going to trade in your car when it has 75k miles on it, it may not matter much. But even in that context I'd still use a synthetic just for the knowledge that my car is getting the best lubricant. Just my 2¢.
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