Oil Change and Oil Pressure on 8BA Flathead
Thread Starter
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Mountain Pass
Joined: Sep 2017
Posts: 123
Likes: 37
Oil Change and Oil Pressure on 8BA Flathead
Hi All,
Time for some dumb questions....
What oil is everyone using 20/50 etc, I've seen various comments across the web (as the manual is not using multigrades) and some recommend thicker oils to help with oil pressure?
I've topped mine up slightly (very little new oil) and seen that the oil pressure gauge now doesn't run continuously in the middle where is was previous...It is always low at idle and picks up on the run, but now only moves when you rev the motor. I've seen some people get into arguments at this point over flow and pressure saying as long as you have flow, ignore the pressure gauge etc!
Also can I check that the filler/breather tube is the best point for filling the engine with oil..??. (I told you there was going to be dumb questions)
Time for some dumb questions....
What oil is everyone using 20/50 etc, I've seen various comments across the web (as the manual is not using multigrades) and some recommend thicker oils to help with oil pressure?
I've topped mine up slightly (very little new oil) and seen that the oil pressure gauge now doesn't run continuously in the middle where is was previous...It is always low at idle and picks up on the run, but now only moves when you rev the motor. I've seen some people get into arguments at this point over flow and pressure saying as long as you have flow, ignore the pressure gauge etc!
Also can I check that the filler/breather tube is the best point for filling the engine with oil..??. (I told you there was going to be dumb questions)
Lead Driver
Joined: Oct 1999
Posts: 6,776
Likes: 553
From: Kalispell, MT
You'll get all those same opinions here that you found online.
20/50 acts like 20 wt when cold and like 50 wt when hot.
Running straight 30 or 40 wt is a middle of the road approach.
All are fine in the engine... guys try different oil viscosity according to how much the truck leaks on the driveway/shop floor.
Not sure what you mean about the breather/oil fill tube question. It's the only place you can add oil to the engine.
20/50 acts like 20 wt when cold and like 50 wt when hot.
Running straight 30 or 40 wt is a middle of the road approach.
All are fine in the engine... guys try different oil viscosity according to how much the truck leaks on the driveway/shop floor.
Not sure what you mean about the breather/oil fill tube question. It's the only place you can add oil to the engine.
Parts Nerd Extraordinaire
Joined: Sep 2010
Posts: 4,367
Likes: 1,785
From: Western NY
There are many opinions/thoughts, but I run straight 30 with a ZDDP additive in my flatheads and have been happy and I feel it matches up pretty well with the manufacturers intentions. My pressure starts at just a hair above 30, and drops a wee bit as it warms - as expected.
Thread Starter
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Mountain Pass
Joined: Sep 2017
Posts: 123
Likes: 37
It just made me question, was I doing right lol. I know I can trust people on here, I’ve never been let down yet!
Lead Driver
Joined: Oct 1999
Posts: 6,776
Likes: 553
From: Kalispell, MT
Got it! Yep the 40's oil cap was combined with the fuel pump stand at the back of the engine. The change in the late model flatheads also rerouted the crankcase ventilation. Swapping parts early/late can cause other issues that need to be solved.
Fleet Mechanic
Joined: Jun 2020
Posts: 1,907
Likes: 763
From: Hillsborough NJ
Following…
In my EAB I’ve been running 20/50. I installed a mechanical gauge and I see pressure in the range of 30-40Lbs cold. When it warms up, the idle pressure is very low, 5lbs or so, but goes up at speed. I’ve been told to expect 10lbs per 1000RPM, so at idle (500 RPM) 5lbs is ok. I don’t have a tach but at 55mph I get about 40lbs so I think that may be ok.
I too am interested in what folks have to say.
In my EAB I’ve been running 20/50. I installed a mechanical gauge and I see pressure in the range of 30-40Lbs cold. When it warms up, the idle pressure is very low, 5lbs or so, but goes up at speed. I’ve been told to expect 10lbs per 1000RPM, so at idle (500 RPM) 5lbs is ok. I don’t have a tach but at 55mph I get about 40lbs so I think that may be ok.
I too am interested in what folks have to say.
Thread Starter
|
Mountain Pass
Joined: Sep 2017
Posts: 123
Likes: 37
Following…
In my EAB I’ve been running 20/50. I installed a mechanical gauge and I see pressure in the range of 30-40Lbs cold. When it warms up, the idle pressure is very low, 5lbs or so, but goes up at speed. I’ve been told to expect 10lbs per 1000RPM, so at idle (500 RPM) 5lbs is ok. I don’t have a tach but at 55mph I get about 40lbs so I think that may be ok.
I too am interested in what folks have to say.
In my EAB I’ve been running 20/50. I installed a mechanical gauge and I see pressure in the range of 30-40Lbs cold. When it warms up, the idle pressure is very low, 5lbs or so, but goes up at speed. I’ve been told to expect 10lbs per 1000RPM, so at idle (500 RPM) 5lbs is ok. I don’t have a tach but at 55mph I get about 40lbs so I think that may be ok.
I too am interested in what folks have to say.
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Thread Starter
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Mountain Pass
Joined: Sep 2017
Posts: 123
Likes: 37
Ok, update…. I’ve changed the oil filter, replaced the seals, and made a gasket for the belly pan ( just the round one). Pulled the oil pickup basket and checked it. All clean, a little sludge in the bottom of the belly pan, but not much at all. ….
put new 20/50 classic car oil in and ran it for a few seconds. No problems, leaks or noises. Checked the dip stick and kept topping up until right.
now running continuously at 30 on the pressure gauge no matter what speed or revs!! Happy camper again 😁
put new 20/50 classic car oil in and ran it for a few seconds. No problems, leaks or noises. Checked the dip stick and kept topping up until right.
now running continuously at 30 on the pressure gauge no matter what speed or revs!! Happy camper again 😁
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Fleet Owner
Joined: Dec 2000
Posts: 25,378
Likes: 5,387
From: Central PA
That's good. Lucky you have a real oil pressure gauge. In 1954 F-100's got an idiot light for oil pressure as well as an idiot light for the generator charging. F-250 and up still had gauges.
Fleet Mechanic
Joined: Jun 2020
Posts: 1,907
Likes: 763
From: Hillsborough NJ
Ok, update…. I’ve changed the oil filter, replaced the seals, and made a gasket for the belly pan ( just the round one). Pulled the oil pickup basket and checked it. All clean, a little sludge in the bottom of the belly pan, but not much at all. ….
put new 20/50 classic car oil in and ran it for a few seconds. No problems, leaks or noises. Checked the dip stick and kept topping up until right.
now running continuously at 30 on the pressure gauge no matter what speed or revs!! Happy camper again 😁
https://hosting.photobucket.com/images/yy255/shadderszxr/1E1DC93E-2843-4FD4-B102-BE83
3E0DDA.jpeg?width=960&height=720&fit=bounds
put new 20/50 classic car oil in and ran it for a few seconds. No problems, leaks or noises. Checked the dip stick and kept topping up until right.
now running continuously at 30 on the pressure gauge no matter what speed or revs!! Happy camper again 😁
https://hosting.photobucket.com/images/yy255/shadderszxr/1E1DC93E-2843-4FD4-B102-BE83
3E0DDA.jpeg?width=960&height=720&fit=boundsNow if I’m wrong, I’ll eat my words. Either way, your engine sounds healthy.
Tuned
Joined: Sep 2005
Posts: 250
Likes: 11
We run Amsoil 10-40 Z-Rod in both our ‘48 with a 460 and 49 with a flathead I6. You should choose your oil’s viscosity based on the ambient temperatures you expect to drive in. We chose 10-40, because it can operate in a temperature range of 5F to 122F. Oil pressure should climb with RPM generally.
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