The Stovebolt Site Forums The Shop Area Engine Shop type of oil to use

1950, 235 engine will synthetic oil damage the engine or help cleaning it out?

Good question ,It would help clean things out but most likely would cause a lot of oil leaks. Would also make the oil dirty quickly as years of build up from regular oil.If your engine is dirty I would remove valve cover and side cover and clean them and Maybee use a bit of marvell mystery oil with conventional oil first for a few oil changes before considering synthetic.

The reading I've done indicates that synthetic will not damage your engine or it's seals. It can loosen sludge so dropping the pan & cleaning it out would be advisable. Google Synthetic Oil Myths and you'll find a lot of good reading.

Modern oils exceed the original oil specifications.
You do not out in an earlier rated oil in an engine
that requires a later rated oil. Though you can put
in newer rated oil in an engine that requires an
older rated oil. Jeffrey

http://www.pqiamerica.com/apiserviceclass.htm

When I first bought my 54 3100 with a stock 235 I took it to have the new tires put on. While it was on the rack I asked them to change the oil. It wasn't until after the oil change I found out they used only synthetic oil, they didn't even stock regular oil. At first, I panicked. What was this going to my engine. I researched the myths and became cautiously optimistic. A year later and no issues. I can't tell any difference in comparison to regular oil.

I'm curious what oil multi-grades people are using in these engines?

I am just finishing a rebuild on a 261 and live in northern California hills where it gets down to freezing for only several nights out of the year.

20w-50 10w-40 10w-30 ???

I use 15w40.

Everything on my farm runs 15W-40, from the tractor to the lawn mower, and all the cars. It makes things really simple, and 5-gallon cans of the stuff cost lots less per ounce than buying quarts of some mythical mouse milk. No problems for the past 20-something years.
Jerry

Loose bearings can stand 20w50, rebuilt engines should have a 10-30 or 10-40, straight 30 or straight 40 if it gets really hot.

Clean engines can run any type of oil you want, the thinner oils will seep out seals quicker then thicker oils. Dirty old engines should have straight weight, non-detergent oils.

New formula oils have a high detergent level to move as much dirt and particles as it can, as fast as it can to the filters. This is how they get by with 5000+ mile oil changes, that and the engines don't contaminate the oil like our old carbureted engines do. A non detergent oil, will not clean, so the dirt and sludge stays were it is, stuck to everything, but not floating around in the oil. If you add detergent oil, you risk the chance of all that sludge getting loose and flowing with the oil, which could possibly hurt the bearings. Full flow oil filtration would clean it out, but partial or no filtration is asking for trouble.

10w-30 non synthetic

I'm sure a synthetic oil of appropriate grade would do no harm in a stovebolt, but I struggle to imagine it providing any advantage....

Would a synthetic be less prone to gunking up the rocker shaft?

A synthetic oil would be no less prone to gunking up anything when compared to a modern multi-grade oil.

I have been using Rotella 15-40 for at least 10 years. 10W-30 would be similar in regarding "gunking".

What is the cause of rocker shaft "gunking?" Maybe I shouldn't assume it's the oil.

Dirt getting sucked into the valve cover?

Low quality oil, infrequent oil changes, and lack of driving it like you stole it often enough. Sucking in dirt through the valve covers can be a factor if you drive on a lot of dirt roads.
Carl

Accumulation as described by Carl, enhanced by infrequent oil changes of non-detergent oil.

And, as I think Carl alluded-to, not running your engine for at least 30 minutes after the engine warms up (in other words, short trips).

15w40 in the 216. Will try 10w30 in the newly rebuilt 54 235 and would have no problem going w/15w40 should the 10w30 not perform to my liking, i.e. maintain proper oil pressure at all temps and keep the innards quiet.

I have been accused of many things and have been called many unsavory names, but an alluder?! That will not stand!
For shame, Tim! I thought we were good.
Carl

Much better than being a deluder, Carl

Nothing wrong with alluding.

I am accusing you of good things, as usual.

I had a 1991 mercury topaz from new and at 110 thousand km.66 thousand miles my valve cover started to leak.the cover had a gasket built into it and was 200 plus to replace .I went to the junk yard and got a older cover for 5 bucks and a new gasket as the old cover required a gasket.I cleaned the cover strenuously.changed the aluminum cover and the origional cover inside was shinny like new aluminum .The car from new had synthetic oil and once seeing that synthetic keeps the innards very clean .sorry for the long story .

You get 100 internet points for working a 1991 Mercury Topaz into this thread.

Well done.

what I do know about synthetic oils is, at least one brand of industrial gearbox states in their manuals, that if a synthetic oil is used, you could increase the load by 25%. And as far as keeping the engine clean, that is the detergent, not whether or not it is synthetic. Also, if you are breaking an engine in, most cam manufacturers recommend using mineral based oil for the break in. I wondered why this was, so I asked Crane Cams, and the fella said it doesn't provide enough "TRACTION" to allow the lifters to spin and bed in properly.

My '01 VW beetle 1.8L Turbo motor has 45k miles and looks like it has 145K. Some engines just gunk up inside, some don't. I have run Mobil One in the bug since new due to all the short trips around town.

How many points is a bug with?

15 internet points.

Even full synthetic won't protect you from short trip issues. It will delay the sludge build up but it'll eventually fail. I believe that falls under the severe service heading that requires more frequent oil changes.

I had a '65 Furd Falcon, and it sucked.
How many points do I get?

My apologies to you for my inexplicable truculence.

You get 7. That is a sucky car but you are just piling on.

The 100 points for the Mercury Topaz were awarded not just for the general suckiness of the car, but also for the complete randomness of mentioning it in this thread in this board.

Had long chat with machinist about this after rebuild. He recommends Rotella oil, for any hydraulic lifter motor. Apparently most cam manufacturers like it due to the additives that are still in it.

I use Rotella 15W-40 in my '49 Chevrolet 3100 with a 216 cu.in. 8-10psi at idle and 15-18 on acceleration. Like the Rotella because of the zinc level and other additives that help protect these flat tappet engines.

Tim

Synthetic oil won't damage your engine. Depending upon the additive pack in the oil, synthetic oil may or may not clean your engine better than the mineral oil you're using now. If you're not having extended oil change intervals, you probably won't get the benefit of synthetic oil.

Mobil 1 video - Is Synthetic Motor Oil Good for Everyday Cars?

See Selection of the Right Motor Oil for the Corvair and other Engines

Older, flat tappet engines should use Heavy Duty Engine Oil and I use Rotella T 10W-30 in my slant six.

Engines depend upon oil FLOW for lubrication and pressure is related to flow and viscosity. Using and oil that is too viscous just means that more oil gets recirculated back to the sump by the relief valve.