Oil---Synthetic or Natural

jjtarnow · #1 (**permalink**) 10-25-2004, 06:56 PM

I have a 514ci and my engine builder recently suggested I change from Royal Purple synthetic (had it since new) to Pennzoil Racing (natural..not sythetic). The reason? He thinks the non-roller cam 514's do better with natural oil vs. synthetic. Any thoughts? A 460 owner wrote me that when he went from synth to regular his motor started leaking (odd..usually happens the other way around!)...thoughts?

Josh

clayfoushee · #2 (**permalink**) 10-25-2004, 07:39 PM

After witnessing endless debates on this topic, and reading a lot of tech stuff, the only reason for staying away from synthetic in older tech engines is the leak issue. It seems hard to dispute the results of endless technical papers that show that the synthetic stuff is far superior from a durability, and "slipperyness" standpoint. However, it seems to be the "slipperyness" that causes the leak issues in older technology engines.

However, I'm staying with Valvoline conventional 20/50, for the leak reason in an old FE. Most of us change our oil maximum every 6 months, regardless of the mileage, or every 1-2K miles, and the coventional stuff doesn't have time to break down in that time.

Dennis Kelley · #3 (**permalink**) 10-25-2004, 08:14 PM

I use conventional Castrol 10W30 as recommended by the machine shop and my father. I change the oil every 1000 miles so its not realistic to use synthetic. If I was going to road race this engine in high temp and extreme condition I would probably use synthetic. My Wife's car and my every day drive get mobil 1 synthetic just because I change it every 6000 miles. If your motor runs good on Royal Purple and doesn't burn oil I wouldn't change it but thats just my opinion.

cobrashoch · #4 (**permalink**) 10-26-2004, 06:02 PM

After reading endless pros and cons on this issue it comes down to one, and only one question to me. How long are you going to live with the engine? If you are giong to tear your engine down as I do every 10K or 20k then mineral oils win. If you are going the distance, say 100,000K or better, then the synthetics win.
Unless you are racing of course. Then the synthetics win every time, for lots of reasons. Another thing, if you are running a roller lifter motor, (sans-385?) oil is the guy that cools your complete valve train. And again, synthetics direct heat away from the valve train a bit better.
I've had bearing problems/issues on the bottom end with Royal Purple oils and soft bearings, but I had good results with Mobil-one 15/50 using those same bearings.
Down through the years, I've never had a engine failure that I know of, that I can relate to a mineral oil failure. And believe me I've really screwed some engines up bigtime too!
I guess the short answer to this question is to be realistic about your intended useage. Good luck!
cobrashock

Mr.Fixit · #5 (**permalink**) 10-26-2004, 09:25 PM

Honestly, most real racers I know, weveral of which were sponsored by the machine shop I worked in, used mineral oil. Valvolene racing was the most popular.

If I was going to run any type of endurance event, or if I lived in the super duper cold climates, I would probubly run synthetic; other than that, just keep it yellow and get it warm before you stand on it.