The Stovebolt Site Forums The Shop Area Engine Shop What oil weight?

I have a 1955 235' in my 1951 3100. Which oil weight works best with these older engines? I know that shop manuals talk about heavier oils but how does that translate to the newer oils that we have today. I Just want to make sure that i am not missing anything important.

Thanks for any info.

I always used 10W30 in my 261. This was in a 2 ton truck. Never had any trouble with excessive oil consumption.

Also I think you should use detergent oil. The oils they had when these engines came out weren't as good as what we have today, in my opinion.

Using detergent oil in an old engine that has only used non-detergent oil might not be a good idea. Bad things that have settled out might be brought back into suspension.

What type of oil has been used in the engine?
Do you have an oil filter on the engine?

Nonetheless, which Shop Manual suggests higher weight oils? Higher than 30 weight?

Some of us use higher weight (multi-viscosity) oil in an attempt to raise the oil pressure (30W50, for example).

Here are the oil weights recommended in the first year of the high-pressure 235 truck engine.

Hey 53guy - If you are not sure of the condition of that 235 or what oil was used in it, I suggest 30W Non- Detergent. It's warm over there in Hawaii right? Straight 30W will be fine. I agree with tclederman that the detergent oil will loosen up all the old gunk and circulate it thru the motor, then you got real problems.
I got a friend in kauai. "Steel Grass Farm." Have you heard of it?

The engine runs great, sounds like a 235. But I haven't really gotten into it (haven't needed to). It does have the external oil filter. If it needs thicker oil I want to make sure I'm not causing excessive wear on it. I think I put 10w-30 in it last time I changed it. Thanks for the input.

PS. I don't know of "steel grass farm" but Kauai is gorgeous.

At least you don't have that much "highway speed" to worry about
Tough life

i use rotella 30 wt in my 40 and 51-6100. i use rotella 15-40 in the 51-350 and the 720

Just to confirm, the higher the # the thicker the oil, correct??

Also, I'm using a 30 wt. oil now. What's the thickest I should go to in my 216 to help reduce slight smoking?

Thanks guys,

Spot

I've always been a fan of Castrol 20w50. The first number is the weight or thickness of the oil. The higher the number the thicker the oil. The second number is the lubricating ability. Or it sticks like a 50 weight but flows like a 20 weight.

With the rope seals you want to run as thick as you can.

20w50

equivalent to a 20 weight oil's viscosity when "cold" (0 degrees C)

equivalent to a 50 weight's oil's viscosity when it is "hot" (100 degrees C)

After turning wrenches for over 40 years I hope I have learned some thngs about oil and such. In warm weather the heavier weights are good to use especially if you are really working that engine. If not a good 10-30 works very well or a good quality 30 wt. You might look at Lucas products which helps keeps things lubed when you first start up. I have seen more than one engine suffer from lack of lube when using 20-50 wt in cold or very cool weather as it takes too much time for the oil to circulate to the cam and such. Harder on the starter too. Also you use more fuel in colder weather as it harder for the oil pump to circulate that heavy oil so you need to put your foot further down on the pedal to get it moving. OHC engines really suffer when to heavy of an oil is used. They "knock" on the upper end until the oil warms up some. Anyhow, just my two cents worth. Henry

Thanks for the info TcLederman and Henry G.

Spot