The Stovebolt Site Forums The Shop Area Engine Shop Synthetic oil?

I am sure this has been asked before, but I just had my 235 engine rebuilt. I am almost at 500 mikes with engine break in oil. One shop said 10-30 with zinc additive. Another shop said I should put synthetic oil since it's basically a new engine. Any thoughts?

10-30 with a little zinc would be my choice, or 10-40 if its hot where you are. Synthetic will a little to slick for proper ring break-in, plus its fairly thin and tends to leak out more the conventional oil does. The oil filtering system, if it has one, is not as good as modern engines, so the time to change oil will still be fair quick so the advantages of synthetic oil will not be seen ( longer run life).

Joe

A stock 235 doesn't need a zinc additive. If you want to run synthetic go for it. Synthetic oil is superior to non synthetic in almost every way. Some reading.

The link above pretty much explains away the myths of too slippery or leaking.

Gotta love a good oil thread........No matter the forum they are all the same.

Same goes for the thread in driveline on gear oil choices...........all the

Agreed. If you feel you need the extra ZDDP, there are synthetics out there that have a higher content, usually in racing oil lines, like VR-1 from Valvoline.

It all depends on how full your pocket book is.
As stated syn oil is superior to dino oil but do engines that were designed and built to run on a 20w non detergent dino oil benefit with the use of syn oil? Keeping in mind that they came out of the factory without an oil filter?

IMHO, unless your engine is practically leak free you'll be spending more $$$$'s keeping the syn oil topped off as opposed to, say a 30w,10w30 or 15w40 Rotella dino oil that can be had about as cheaply as any oil and is of great quality.

Due to the design of these old stovebolts it's arguable whether syn oil extends the engines life anymore than a qulity dino oil so the benefit may be inconsequential...

But then again, if you run the same oil in all your engines and it happens to be syn, mo power to ya, it then may be cost effective.
Good luck
Dave

After you are sure the rings are seated, run the oil you like. I have read enough of the oil information to know, synthetic is to slick to properly break in rings. That does not mean it's not good oil or you shouldn't use it, just use it after you get some drive time on the rings. I have used it in my 1970 250, and it did seep out and drip more then the standard 10-30. It still got dirty just as fast and needed changing just as often, so the cost versus extended life wasn't there.

And on the same note, once you are sure the cam and lifters have seated, zinc is probably not needed due to the weak valve spring pressure and cam profile. You could get away with half a bottle per oil change, or even none if you are willing to risk it. It depends on the camshaft and lifters and who made them.

Just don't expect the 235, even though its fresh from a rebuild, to treat oil like a newer engine does.

Joe

I'd have to disagree. Synthetic being "too slick" is a myth. Read the link I posted above.

I should stay out of this conversation but I just have to throw my 2 cents in.
Its not about agreeing or disagreeing for me. Its a matter of economics. As my mathematic teaching daughter says "do the math"

Since 1982 EVERY car I've had has ran on Castrol 10 W 30 here in the sunny S.C. I changed the oil, and filter, every 5000 Miles.
I've put over 200,000 on all of them and on my current 2000 Silverado it just turned past 304,000 and still doesn't leak or use oil between changes.
With the price of Synthetic vs Castrol I cannot justify the expense for the small percentage of actual "synthetics" in a quart of oil. Its a "cash cow" for the manufacturers.

In raising a child, you start teaching it at an early age which helps determine its future.....
What you do to an engine in "raising" it determines the "future".
(you can get a lemon in each)!

One cannot wait until there is smoke coming out the tailpipe and then try to fix it with a can or bottle of "snake oil". Its to late!
For me, I'll keep the money in my pocket and buy biscuits.

Zinc additives do not hurt during break-in.
But, it is not needed at all for normal driving 216/235/261.

Amen, Alvin, regarding synthetic oil in any stovebolt engine.

Thanks everyone!!

Oil discussions come close to politics and religion. So please consider the following as "Opinion" mine, of course, but still opinion. Any one remember EP oil from about the late 1960's to the middle 1970's? I know I am dating myself. We used it for the leaky 216 in my truck and my brothers GMC(engine unknown). Cheap and purchased by the case. A bit like a slow motion oil change(hey look ma no filter on these motors). Worked fine. Pennzoil(yep that brand), was a common oil used by many at the same time. Problems? Some had huge sludge build up in the valve covers and around the valves and springs. Other wise...none. The difference from then and now? Detergent oil. And the odd PCV system. Conclusions? Detergents work(this used to be a hot oil topic) PCV? It works too. The engines I see are cleaner, much cleaner. Most of the sludge was from short hops(water condensation) But that detergent stuff makes a difference. Look at the API codes. Spend what you need and drive it. Synthetics work in properly sealed motors, and last because the contaminations are better controlled(do not expect that to happen just because you rebuilt a 65 year old motor). The one advantage synthetic oil has, the polymer is longer and stronger. The other less often noticed difference is the viscosity is a bit more stable over a wider temperature range. My 2 cents have been spent, enjoy.