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I have a 52 1/2 ton with an early pressurized 235. Solid lifters. Ran all summer with just a bit of a click from the lifters. 10-30 oil and no troubles. So now we get some cold weather and I go out to start and let warm up. It is cold: 10 degrees F. Pull the choke, pump the pedal a few times and it starts right up. But what worry's me is the oil pressure is slow to build up. 2 minutes and only 15 psi at a fairly fast idle. Choke is still pat way on and...a lot of valve clatter. Not what I hear normally. I let it run for a while longer and the pressure comes up and the noise goes down. Some any way. Is this normal? I did own and drive a 50 1/2 ton many years ago but I don't remember this on cold mornings. Any thoughts?

yes, pretty "normal" that the oil is way thick in winter, you could run lighter oil for the winter if you'll be using the truck, or you might want to consider some type of block heater if you're gonna park it outdoors in freezing temps

Bill

I respectfully disagree, With colder weather, oil pressure should be higher not lower because the oil is thicker.

is this the first winter that you have owned your truck..

Higher viscosity oil takes longer to circulate in winter (regardless of what the gauge says)


c.d.p.

Yes first cold winter. Lighter than 10-30? I only have 30 psi when warmed up all the way. Engine is solid but has some wear on it. As long as it gets quiet when fully warmed should it be OK? Would you recommend 5-20? I suspect old heavier oil in the line to the gauge for slow pressure build. Does that sound about right? Maybe I am thinking this too much. Any thoughts are welcome. Thanks!

One advantage of synthetic oil is that it isn't so temperature sensitive.

Dennis

Yes, a higher reading on the gauge should be seen at start-up in cold conditions on early high-pressure 235s.

30 psi when warmed up would be nice/normal.

A low pressure when cold may not be ideal, but 15 psi is not dangerous, especially if the pressure raises to "normal" at warmed-up temperature. Just continue to let it warm up before driving it.

Thanks to all for the response. Slow warm up is what I expected.

Can you imagine when your truck came out in the 50's they use 20W oil. Yes, if you don't plug it in then it will make noise until it is warmed up and circulating.
Depends how tight your engine is whether synthetic will help or not.

Like Jackpine said, 20W was recommended down to +10 deg. At -10, they recommended 10W plus 10% kerosene (or 5W if available).

I use 10W-30 but put a magnetically-held heater on the oil pan when it gets below zero or so.

A frost plug heater under the intake manifold makes all the difference in the world for smooth starting and idling when it gets below 20 degrees, at least for my 261.

For early high-pressure 235/261, GM recommended 10W at 0 degrees F or 10W-20/10W-30 (those multi-grades make sense). Below 0 degrees F, GM recommended 5W or 5W-10/5W-20 (those multi-grades make sense).

By the way, I wasn't recommending adding 10% kerosene in very cold conditions! But we did add kerosene to the oil for an "engine flush" when I worked at a service station in high school about 1960! I think it was a good way to develop oil leaks!!

I put a newer model 250 in my '59 that runs pretty low oil pressure anyway. I started using 20-50 weight oil in the summer to increase the oil pressure. When I started it on the first real cold morning this winter it acted the same way as yours did. I changed to 10-40 for the winter and have been using a magnetic oil pan heater on cold nights and it has solved the problem. My engine only runs about 25 lbs.pressure when warmed up and going down the highway and less than 10 lbs. at idle but it isn't using any oil so hopefully I can get another year or 2 out of it. One nice thing about it is that most people throw away 250's and replace them with V8's so they are cheap to replace. 235's aren't that easy to come by though.

Thanks to all. I went with 10-30 and found another bit of dirt in the line to the rocker arms. Cleaned out the line and the "noise" was cured. Slow build up of pressure has gotten better and no more worries. Just a note on inline 6 engines with a lot of miles/wear. They will run and work. They will tolerate low oil pressure better than any thing else. But..when they are done they will do the strangest things. I put 450k on a 258 Jeep. Most was hiway and easy cruse miles. But at the end when I went over 70 MPH it pushed the dip stick out and pumped 4 quarts out in 20 miles. Was a mess to clean up. The only good thing was I had an oil pressure guage and when it started to bounce I knew something was wrong. Stopped and added oil before any catastrophe. Worn rings any one? Thanks again!

I think your situationis not normal at all. I am wondering if you have a restriction on the oil intake side, maybe a bunch of stuff on the sump screen. These old engines should register their highest oil pressure after a cold startup.

truckernix: Old thick and sludgy oil in the line to the gauge. Cleaned the line out with a bit of air and..pressure comes right up. Still have the 30 Lb gauge so it reads pegged when cold but have 20-25 Lbs at idle all warmed up. On some hot summer days it will go to 15 but so far so good. Pan has been pulled to change the main bearing seal. That was a good time to check and clean the screen. I have had a few bits of dirt get to the rocker arm feed line. They are a mystery cause the engine is very clean in side. My best guess would be the rocker arm shafts them self. Good news? I am very good at removing the rocker arms and line and have become very good at setting the valve lash. So there has been a benefit from all of this.

the old rule of thumb as you need minimum of 10 psi for every 1,000 rpms. So if you idle at 700 rpm you need 7 psi. If you run 3,000 going down the highway, you need 30 psi. But, those are just what I always heard growing up, thought I'd share. I've had many old motors run for years with 10 psi at red lights and 25 or so psi going down the highway and I know the rpms where higher than 2500 (likely more like 3500).

That is good news to here you have it solved. Congrats.

That is useful information. I am right at the point you are talking about. Just give me a couple good years. lol
When I first bought my truck a couple of years ago, there was no oil getting to the rockers on the 235 that was in it. I drove it for about 2 weeks and between 500 and 1000 miles that way before the rocker assembly disintegrated going down the highway. It was full of oil and had good oil pressure and didn't even sound bad til 10 minutes before the incident. I was really impressed that the engine could take that kind on abuse.

So to not scare any one with a 235 or a 216 concerning the rocker arms and shaft. You can pull the breather from the valve cover and look at the rocker arms directly. If you have oil flow at idle you can see it on the front 2 or 3 rockers. If you can not see the oil flow then pull the valve cover and find out why. Simple and easy way to stop the worry. The valve cover gasket is cheap and might even take a few remove and resets with out leaking. If you have mechanical lifters you will pull the valve cover off to adjust valves any way. You can see the oil flow very well at that time. ME? I just get fussy about new noise or new readings from my truck. Typical for a new, to me any way, project to have some teething issues to begin with. Just how do you think I learned to change a main seal any way? Yep it made a mess in a friends drive way. Got to clean that up too.