VCCA Home Forums TECHNICAL - 1945 AND NEWER 1949-1954 Oil for my 235

I am about to change the oil in my newly purchased '51. The current oil is black as coal, and in dire need of freshening. Can I use detergent oil, and a multi weight? I know this topic has probably been beaten to death, but I need to know! I don't believe this engine has been opened for a long time, but I do know it is not the original, as it is a 235 in a 3spd car. The last owner did not know much about it's history, as he is a used car dealer and just took a chance on selling an old Chevy he found at a swap meet.

Mike,
If it were mine I would use 10W-30 oil,which is detergent.I would change it again in about 500 miles.Detergent really will not clean your engine but just hold the dirt being formed in suspension.It will not loosen gobbs of sludge.Probably would be good just to remove the valve cover and see how sludged the rocker arms and the top of the head is.If its a 235 I would guess its probably a later 235 with full pressure oiling.If it is the oil pressure will be pegged up at 30 pounds when hot and above idle speed.

Gene's advice is good as usual. One of my first tasks when getting a new "old car" is to pull and clean the pan. Also the oil pump screen. Amazing, how much sludge you might find.

Maybe I am too old fashined and heard too may tales of long long ago, but this topic is as old as the hills and the wisdom I have been "taught" was never never start using detergent oil in an engine that grew up on non-detergent oil. The reason that was given to me is that the detergent oil will cut the built up carbon particles loose and circulate them through the bearings (rods, mains and cams) and sand blast the hell out of the soft bearing material.

That being said, I must tell you that I am doing precisely that: using detergent oil in my 216. However, the difference here is that I took the engine all apart and "hot tanked" the block (dipped in a hot tank with lye based cleaning detergent, basicly sodium hydroxide or calcium Hydroxide) that will eat up the carbon deposit from the inside of the block and crank. Also I sand blasted the cam shaft and sand papered and scraped the inside of the pistons and rods. Basically the engine was claean enough to eat off when I reassembled it.

I added a pint of marvel mystery oil in my 61 235 and ran it for about 500 mile and then changed it again and that worked great for cleaning...Oscar :grin: :grin: :yipp

I have noticed that the oil in the 235 engine , no oil filter, gets black much sooner (fewer miles) than the engines in the new Chevys. I suspect that is because they are dirtier as far as combustion products staying in the engine, I change oil every 1200 miles or so.

Marvel Mystery oil fixed the sunken lifter in my F-RD. It is good stuff. I also take 2tbs every day to keep me regular

Just kidding.

Marvel Mystery Oil is solvent based and would be more prone to lossening up sludge.I do use it for special applications but if using in a dirty engine I would change oil after a few hundred miles.
I would assume that the oil in our older engines turns black is from somthing related to inefficent burning of the fuel.The diesel engine is even worse in this department.

Yeah, if you take a couple of teaspoonfulls of MMO a day you will be more than regular, it will improve your bad breath also!
I like to fog the engine before storage by pouring a small stream into the top of the carb, it seems to keep the valve train loose and the rings free, may just be a feel good thing, but it makes me feel good!

I will add what little I have been told about the Detergent -Non detergent discussion. In 1950 I worked for a Shell oil station, as the firm I worked for had several stations and 3 different brands they consolidated under the Union 76 brand. We had a products meeting in which different products were discussed. The main discussion was "Royal Triton" a new HD detergent being marketed at the time by Union. The main item that I recall was the warning that Royal Triton should not be marketed to owners of cars with high mileage ( I do not recall what High Mileage meant), the reason being that the HD would flush accumulated sludge and other contaminants, damage the engine which would then require replacement. If my memory serves me correctly we were also told that Union 76 had a reserve fund to handle this potential problem.