Switch to Synthetic Oil

Stosh:
I'm having my Cleveland rebuilt. I spoke with several machine shops before I started. The concensus of opinion (with moly rings) is about 1500 miles before the change to synthetic.

GOOD LUCK

With moly-filled rings, the engine should 'break in' almost instantly. I've seen real-racers run a brand-new engine up and down the access roads for 10 minutes to free it up, then go out & race with good results. If you're also changing to a new cam & lifters, a specific break-in period according to the cam grinder should be followed. Change the oil & filter afterwards. If, god-forbid, you selected chrome rings, the break-in period may exceed 10,000 miles, or never.... Ford blocks seem to get harder & slicker the further they're bored. Chrome rings are used mostly for very dusty areas like in dirt track modifieds, or tractors.

I recently switched to synthetic engine oil and (as some predicted) my engine leaks are now significantly pronounced. If I were to switch back to regular oil, do you know if the leaking would slow down or has the damage already been done?

Just wondering as I plan to switch back anyway.

Thanks,
Bob Eaton

Bob, synthetic oil is always thinner than regular oil, so it seems to leak easier. And synthetics seem to have more detergent qualities so they remove varnish that may play a part in sealing up older engines. I have no idea if switching back would stop any synthetic-caused leaks. All you can do is try it and report back.

Hi Stosh, I can't give you specifics on this, but I know some synthetic oils are not compatible with certain polymer seal materials and can either soften or harden them. If you're using Mobil 1 this is not your problem, as I do know for sure that Mobil 1 does not cause this problem. Good luck...Al English

Al - Thanks for the info!! With all the great feedback this post has generated, I think that I'm going to go with Mobil 1. Next question forum members!! - Do I need a specific filter for synthetic oil? I'm staying away from Fram filters & am leaning towards the top Purolator or Motorcraft filters. Thanks again guys & gals, you folks are the best!
Stosh

quote:

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Originally posted by Al English:
Hi Stosh, I can't give you specifics on this, but I know some synthetic oils are not compatible with certain polymer seal materials and can either soften or harden them. If you're using Mobil 1 this is not your problem, as I do know for sure that Mobil 1 does not cause this problem. Good luck...Al English

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Stosh:
If you elect to go with Mobil 1 the correct filter is part # M-1-301


P.S.
The machine shop just finished my 351C and I ordered a Centerforce Cluth and flywheel from Gary Hall. Should be on the road in 3 weeks. Take Care

I'll point out that quite a few high performance cars such as Vipers, Corvettes, etc now come from the factory with Mobil 1 in the crankcase. The old rule of thumb was that synthetic oil was "too slippery" to break an engine in. The factory engineers must have found that to be a myth.

Hi Andy, You are correct about the new cars shipped with Mobil 1. Oil that's so slippery the engine can't break-in.......sounds like marketing BS doesn't it? But on the other hand I've seen enough first hand, and heard a lot more stories, to know there's more going on than just myth and legend. I'm still looking for answers on this subject. The cars that are shipped with synthetic oil are all high-end vehicles. It has become pretty common for manufacturers to hot test, and in some cases break-in, newly built engines. This is especially true in high-end products. Possibly the engines in the cars you mentioned are initially run and broken-in with mineral oil at the factory? Or maybe it's a case of having the right bore finish with the correct type of ring. At this point my feeling is that using mineral oil during break-in isn't going to hurt anything. And without knowing all the variables, I don't think it's worth taking any chances...Al English

Al, are you familiar with SAE (society of automotive engineers?) They publish a great deal of information on lubrication as well as other automotive engineering issues. You might want to check out their website and maybe look through some of the latest publications on the subject. It has been a while since I did a lit search on the subject but I'm positive that before the Corvette engineers signed off on Mobil 1, they did their homework. Odds are, that homework turned into a technical presentation at a SAE conference and thereby made its way into the public domain.

[QUOTE]Originally posted by phd507:
[B]Stosh:
If you elect to go with Mobil 1 the correct filter is part # M-1-301


I recently switched to Mobile 1, but didn't know there was some special filter that goes with the oil. Is this correct?? I got a Wix filter, and wouldn't think the type of filter would matter.

I finally wound up going with the Mobil 1 15w-50 & a Purolator PureOne filter. Check out www.minimopar.net/oilfilterstudy.html , someone forwarded this site to me awhile back, it's a great site with lots of info regarding filters/oil types, etc.
It's been over a year now since I first posed the question that started this string, & I can say that I am positively sold on the Mobil1, it's great stuff!!