Detergent or Non Detergent oil? 1954 Chevy 235 inline-6

[SubZero350]

I recently acquired a 1948 Chevy 3100 pickup truck. It was originally equipped with the 216 Stovebolt inline 6 engine but spent many years getting worked hard on a farm. At some point, the farmer removed the original 216 engine and replaced it with a 1954 Chevrolet passenger car 235 inline 6.

I suspect the 235 had been rebuilt at some point prior to the previous owner (to me) purchasing the vehicle 10 years ago. The engine block and head have been painted a non-factory color, and it carries very high oil pressure (30-50 psi, depending on RPM and temperature). It is also very quiet, mechanically, and burns almost no oil.

The previous owner to me (who purchased this truck 10 years ago) ran nothing but non-detergent SAE 30 oil in it while he owned it - believing that the truck still had the stock 216 in it. He put at least 6000 miles on it, with an unknown number of miles being on the truck and 235 engine previous to him purchasing it from the farmer.

I've heard horror stories about switching to detergent motor oil in old engines because it can loosen sludge that can plug up oil passages. However, as I stated, this engine has been rebuilt at some point. I inserted a bore scope camera into the oil pan thru the drain plug but could not determine if there was any sludge laying in the bottom of the oil pan due to inadequate lighting.

The question is: would it be safe to use a modern detergent motor oil in this engine at this point? I will, of course, be adding the recommended amount of Zinc/ZDDP due to the presence of a flat tappet camshaft.

 

[sloinker]

That engine won't know what to do with itself with modern oil. Buy some Valvoline VR1 with the zinc already in it at whatever weight makes you happy. Maybe some of that new Valvoline that cleans the ring lands....

 

[supton]

Are the oil pan and valve cover gaskets in good shape? I'm wondering if pulling them would provide a real fast answer as to if anything has built up or not.

I probably would go down the path of using detergent oils, on the basis of, why continue on a path that will likely lead to issues? Does this have a full flow oil filter? If so, I don't see how it would make it past the filter to plug anything up (now plugging up the filter could happen, I guess, and then when in bypass flow junk to places--but short OCI's and filter examination should show if that is an issue, no?).

Is ZDDP really needed? I thought that was needed for high pressure valve systems. I'd probably be more worried about lack of lead in the gas and valve seat erosion, which may not be a problem on a lightly used engine.

 

[JavierH19]

Does that replacement engine have an oil filter? In those years they were optional.

 

[eagle14]

I recently acquired a 1948 Chevy 3100 pickup truck. It was originally equipped with the 216 Stovebolt inline 6 engine but spent many years getting worked hard on a farm. At some point, the farmer removed the original 216 engine and replaced it with a 1954 Chevrolet passenger car 235 inline 6.

I suspect the 235 had been rebuilt at some point prior to the previous owner (to me) purchasing the vehicle 10 years ago. The engine block and head have been painted a non-factory color, and it carries very high oil pressure (30-50 psi, depending on RPM and temperature). It is also very quiet, mechanically, and burns almost no oil.

The previous owner to me (who purchased this truck 10 years ago) ran nothing but non-detergent SAE 30 oil in it while he owned it - believing that the truck still had the stock 216 in it. He put at least 6000 miles on it, with an unknown number of miles being on the truck and 235 engine previous to him purchasing it from the farmer.

I've heard horror stories about switching to detergent motor oil in old engines because it can loosen sludge that can plug up oil passages. However, as I stated, this engine has been rebuilt at some point. I inserted a bore scope camera into the oil pan thru the drain plug but could not determine if there was any sludge laying in the bottom of the oil pan due to inadequate lighting.

The question is: would it be safe to use a modern detergent motor oil in this engine at this point? I will, of course, be adding the recommended amount of Zinc/ZDDP due to the presence of a flat tappet camshaft.

An engine of that era will have very low valve spring pressures, flat tappet or not. Don't sweat needing extra zinc, as it's immaterial. and having run it about 6k on non-detergent oil I also would not be concerned about. If it were 60k, maybe so. Newer oils are not likely to cut loose a chunk of sludge.

Any pix you can share?

 

[addyguy]

HDEO 10W-30 all day in that rig, and just do some short intervals to make sure any sludge comes out. Don’t over-think it…

 

[mrsilv04]

Dad has a 1952 Chevy DeLuxe with a 235 in it. I feed it Rotella T4 (white jug) HDEO 10w-30, and change it once a year.

 

[SubZero350]

The engine is NOT equipped with a full-flow oil filter. It did have an external, partial flow oil filter housing that I got with the truck, but it was apparently removed during the rebuild and never re-installed (so the engine is currently running without any kind of oil filter). I do plan on reinstalling it, but I have to get hoses made to do so.

I have already purchased a valve cover gasket and plan on removing the valve cover to check valve lash adjustments.

I did get a few pictures of inside the valve cover thru the oil fill cap:

 

[SubZero350]

More pics...

 

[JohnnyG]

Detergent

 

[zray1]

Mobil 1 15w-50 is the safest oil to run on this era of classic cars. It will gradually clean the engine , which is exactly what you want. We used it extensively at a restoration shop I worked at.

If your winters are severe, use the Mobil 1 0w-40.

Either one has more zinc & phosphorus than typical oils, although I don’t believe that the zinc levels will be anything you need to be concerned about .

 

[CorvairGeek]

While you can check it, aren't all passenger car 235s hydraulic lifters in '54? Can't remember if it was still PowerGlide only.

 

[Kira]

Auntie married a Californian with a '54 Chevy.
I drove it around when I visited in '76.
Not quite a '34 wagon but pretty cool.

 

[kschachn]

Detergent

Agreed. There is no place for non-detergent oil in an internal combustion engine.

 

[hank2]

I'm surely not the Chevrolet expert including the earlier 235 stovebolts. I do believe that in the earlier 235 engines, only the Blueflame version has a pressurized oiling system. Corvette and some trucks perhaps? The other 235's had the Babbitt bearings and mostly splash lube. At some point early on, the 235's with Powerglide automatics and mechanical valve lash got the pressure-lubed version while the manual trans models did not. Hydraulic valve lash may have been standard on all by 1956.

I would first determine if the donor engine from the 1954 car is pressurized or Babbit bearing before deciding permanently on an oil. Perhaps something with above average film strength.

 

[Rogueman2016s]

I’d run a 10w30 or 40

 

[JeffKeryk]

Any 10w30 detergent, Shell Rotella T or Castrol GTX Hot Rod oil will work fine. Those engines run like a sewing machine. I had a 1950 2 door sedan for years; never gave me a problem.

 

[PontiacHO]

It will be interesting to hear how the old rope rear main seal does with a detergent oil. I’m sure if the engine has been overhauled the last 30 years it should have a neoprene seal. Even then, non-detergent oil for that long and changing to detergent is interesting.

 

[bullwinkle]

Picture looks like there is sludge on top of the head-think I would proceed with caution, especially with no oil filter. Short OCIs (no more than 2K), ND oil (unfortunately). Or be prepared to pull the oil pan & clean the strainer...

 

[SubZero350]

I'm surely not the Chevrolet expert including the earlier 235 stovebolts. I do believe that in the earlier 235 engines, only the Blueflame version has a pressurized oiling system. Corvette and some trucks perhaps? The other 235's had the Babbitt bearings and mostly splash lube. At some point early on, the 235's with Powerglide automatics and mechanical valve lash got the pressure-lubed version while the manual trans models did not. Hydraulic valve lash may have been standard on all by 1956.

I would first determine if the donor engine from the 1954 car is pressurized or Babbit bearing before deciding permanently on an oil. Perhaps something with above average film strength.

I went down this rabbit hole shortly after acquiring the truck. The original 216 engine did indeed have babbitt bearings; and in that engine, the camshaft and crankshaft main bearings were pressure lubricated by the oil pump, but the rod bearings were lubricated by dippers.

I posted the casting numbers I found on my 235 engine over on the stovebolt forums and the consensus was the engine block was cast in 1954 as the passenger car version of the 235 that does indeed have the full pressure oiling system, but it is not the higher compression blue-flame engine (unfortunately). That being said, this engine does run very strong, so who knows what was done to it during the rebuild.

There are also some over there of the opinion I should NOT run detergent oil in this engine, especially if the rear main seal wasn't changed from the original rope type to a newer neoprene type seal.