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I just changed the oil on my M37. It has a 251 engine. I looked up in the Canadian manual. The oil capacity is 5 quarts (when the filter is drained and changed as well). When I filled it with 5 quarts (poured 1 Qt in the oil filter canister, and the other 4 in the oil filler neck). The dipstick shows he level to be at "ADD OIL" mark. I ran the truck for a little bit, waited 10 minutes or so, checked the level again, and got the same results. So apparently, I have the wrong dipstick and/or the wrong dipstick tube in my truck.

Can someone with a 251 engine measure the length of the dipstick tube from the engine to the top of the "head" on the tube. I also need the length of the dipstick from where it is attached to the underside of the cap to the low oil mark. Hopefully, that will give me what I need to come up with something that gives an accurate oil level reading.

I can't help you with hour question, but as no one has chimed in here with their thoughts, I would suggest that as long as you know how much oil should be in hour longer motor, you can scribe the correct line on your dispstick. Not perhaps OEM, but would work until you can find out if there is a difference. I have a hunch the dis-sticks are the same, as the sumps are probably the same depth. Maybe the ancillary oiling parts, like the filter system are different, holding more oil. Who knows what other car or truck engine parts have been swapped into these vintage motors over the years. You might check the Steel Soldeirs's forum for more on this. hal

Hi John, I’ll take a few measurements tomorrow when I get out to the shop.
Cheers,
Rob

Thanks, Rob

Ok let me know if this is enough

And the dipstick

Perfect, Rob. Thanks again

Was this a 251 engine? (Not sure if the dipstick set up is the same or not between a 251 and a 230.)

Yup it’s a 251, T249 model

Mystery solved. My dipstick is the same as yours (or at least within 1/4" or so). My tube is one inch taller, causing my dipstick to read low.

Thanks again for the help

Great!
It sure is strange what gets changed out over the years and then leaves us scratching our heads trying to make sense of it.

Interesting twist here:

The manual for the M37 CDN (CDN-VEH-D114) with the 251 engine says "The capacity of the engine lubricating system is 4 quarts (refill) or 5 quarts if the oil filter has been drained or replaced." (Pg 13)

For the US trucks with the 230 engine, TM 9-8030 says "Crankcase (refill) 5qt (When replacing oil filter or filter element, add 1 qt.)" (pg 18 tabulated data" {EDIT} The newer TM 9-2320-212-10 operators manual says the same thing.

I would not have guessed that the 251 with its 2" longer block takes 1 qt less oil than the 230 engine.

John Mc wrote: ↑Sun Nov 12, 2023 1:31 pm Interesting twist here:

The manual for the M37 CDN (CDN-VEH-D114) with the 251 engine says "The capacity of the engine lubricating system is 4 quarts (refill) or 5 quarts if the oil filter has been drained or replaced." (Pg 13)

For the US trucks with the 230 engine, TM 9-8030 says "Crankcase (refill) 5qt (When replacing oil filter or filter element, add 1 qt.)" (pg 18 tabulated data"

I would not have guessed that the 251 with its 2" longer block takes 1 qt less oil than the 230 engine.

That’s strange. I’ll have to take a look at the data plate on the truck and see what it says. Could be a typo?

Nope, not a typo I clued into it when I read the data plate, that the Canadian spec is in imperial quarts/gallons and not US.
So, 4 imperial quarts is roughly 4.8 US quarts.
Only slightly less than what the American trucks call for

Mystery solved!

If you are changing the filter as well, 5 Imperial quarts = 6.005 US quarts. I probably leave more than that in the bottom of the bottles when pouring them.