10W40 too light?

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72bluNblu said:
Mattax is right on about this. There's still a difference, and it can be important.

But more importantly, it doesn't matter in this case

@Dave NEO 's engine is pushing 30 psi even when hot. His engine shouldn't be making any noise because of that pressure, it's high enough.

So the problem likely isn't which oil he's running or what viscosity it is, he should be looking for what/why it's making noise. Maybe the top end of the engine isn't oiling properly, or the valvetrain is out of spec, or the lifters are going bad, or the cam is going flat, etc.
Click to expand...

I wqas just stating how all oils get thinner when hot. I have a hot, low oil pressure situation myself. The engine likes to idle about 1150 and doesn`t ever rattle using 20w50. Not related to bearing clearances, their actually a little tighter than I`d like. Thinking it`s the lifter leaking deal now------------
 
I have yet seen any oil get thicker when hot if that were the case your hot idle oil pressure would be higher than cold i'm not saying it doesn't change with heat but I never seen it get thicker .
 
so say I switch to 15W50 - what might I see if maybe it's too high a weight?
 
Do you have a well pump on your house?


Imagine if it was pumping something thicker than water.
Molasses is good because its extreme, but honey, or ketchup is Ok if that's easier for you to picture.
Now go open a faucet on an upper floor.
How much would flow out compared to water?

What would the pressure be at the pump?
How 'bout at the faucet?

Repeat the above scenario except open all of the facuets on the first floor as well as the upper floors.

Then take these analogies back to the engine and make it less extreme.
 
So you have a fast rate of lift cam and honest to goodness anti pump up lifters and you are wondering why your engine is noisy. If they are real anti pump up lifters, then you must surely have adjustable rockers like they absolutely REQUIRE. The correct adjustment for them is between .002" preload and .002" lash, like a solid cam. I prefer running them loose at .002" lash. Put those fast ramps together with anti pump lifters and that engine will make noise regardless of oil.

If you wanted a granny quiet engine, you should have built it stock.
 
maybe it's just gotten broken in - about 900 on rebuild. I know oil threads can get out of control but I hope most don't mind revisiting this stuff. thanks again for all comments.
 
Mattax said:
Do you have a well pump on your house?


Imagine if it was pumping something thicker than water.
Molasses is good because its extreme, but honey, or ketchup is Ok if that's easier for you to picture.
Now go open a faucet on an upper floor.
How much would flow out compared to water?

What would the pressure be at the pump?
How 'bout at the faucet?

Repeat the above scenario except open all of the facuets on the first floor as well as the upper floors.

Then take these analogies back to the engine and make it less extreme.
Click to expand...
that don`t fly w/ my engine, lighter oil, less pressure--------
 
famous bob said:
that don`t fly w/ my engine, lighter oil, less pressure--------
Click to expand...
Its an analogy to point out the relationship of pressure and flow. Its not an explanation of the Goldilocks for any particular engine
When stuff is flowing it matters where pressure is measured.
How much flows depend on both pressure and viscosity.

The goldilocks for any particular engine will depend on the clearences and temperature.
 
Mattax said:
Its an analogy to point out the relationship of pressure and flow. Its not an explanation of the Goldilocks for any particular engine
When stuff is flowing it matters where pressure is measured.
How much flows depend on both pressure and viscosity.

The goldilocks for any particular engine will depend on the clearences and temperature.
Click to expand...

like I posted earlier, my clearances are actually tighter than I`d like for a bigger engine, w/ hi horsepower . I have converted to full time head oiling, but cant get it regulated down far enough w/o pulling the heads, aint gonna happen till I have to ! Seems to be ok for now, except for the low pressure when hot at idle, fine at anything over idle. I`m just not real happy w/ 18-20 pounds at 1150 idle rpm. Supposed to be good enough tho ____
 
Mattax said:
Do you have a well pump on your house?


Imagine if it was pumping something thicker than water.
Molasses is good because its extreme, but honey, or ketchup is Ok if that's easier for you to picture.
Now go open a faucet on an upper floor.
How much would flow out compared to water?

What would the pressure be at the pump?
How 'bout at the faucet?

Repeat the above scenario except open all of the facuets on the first floor as well as the upper floors.

Then take these analogies back to the engine and make it less extreme.
Click to expand...
On the dairy end of the farm we had a 160ft well of hard water, I know a little about wells, no wells now tho.
 
years ago i had a 390 in a 66 fairlane, always used 20/50 as it was pretty 'loose'. i needed an emergency top up during a long run once and used 10/40 (all i could get) to get me home. that thing was noisier than hell. i changed it back to 20/50 the next day and it was all quiet as before. i know it was a ford but you guys are talking ketchup and molasses so.........
anyway maybe try the 15/50 as suggested.
neil.
 
Dave NEO said:
so say I switch to 15W50 - what might I see if maybe it's too high a weight?
Click to expand...

I have seen nothing but better hot idle oil pressure and a slightly seeping oil filter gasket, doesn`t bother anything.------20w50
 
I run 15-40 moble delvac or shell rotella,i also use a ballwin filter,never have use breakin oil,been a truck mechanic 40 years,we dont use breakin oil at the dealership when we rebuild engines
 
mygasser said:
years ago i had a 390 in a 66 fairlane, always used 20/50 as it was pretty 'loose'. i needed an emergency top up during a long run once and used 10/40 (all i could get) to get me home. that thing was noisier than hell. i changed it back to 20/50 the next day and it was all quiet as before. i know it was a ford but you guys are talking ketchup and molasses so.........
anyway maybe try the 15/50 as suggested.
neil.
Click to expand...


If you look at any "good old" Chilton manual, you'll see that Ford's bearing clearances back then were looser than most everybody else's. I don't know what the purpose for that was, but it's true.
 
RustyRatRod said:
If you look at any "good old" Chilton manual, you'll see that Ford's bearing clearances back then were looser than most everybody else's. I don't know what the purpose for that was, but it's true.
Click to expand...

maybe so the thicker 'cushion' of (also thicker) oil protected the motor from extreme abuse, i know i abused that car every day i drove it.
 
RustyRatRod said:
If you look at any "good old" Chilton manual, you'll see that Ford's bearing clearances back then were looser than most everybody else's. I don't know what the purpose for that was, but it's true.
Click to expand...

Both of my 426 hemi`s had .003 clearance from the factory, was the same after my rebuilds, ran straight 40 and 50 weight for yrs., depending on the small time sponsers I had that furnished it.
 
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