Does oil weight Matter or ? (1 Viewer)

[love2fly]

Well I hope this post finds you all in good health, as for me I am staying busy, which brings me to this post. Today was around 78 degrees so I decide to take the family out for a drive. Not more than 15 minutes later I noticed that when I cam to a stop light the oil pressure was below the first line while at idle. So 20 more minutes later the oil pressure was well dam near on the first line. So I would hold a bit of throttle in to keep it at the fist line.
I have a dizzy from Troll Hole installed and was thinking that this electronic dizzy maybe failing but the truck was doing fine as in response to power.
So as we all have had the good old "OH ****" flash into ones head as I, right away remembered that I used GTX 10-30W engine oil at the last oil change that during the winter months were I usually use GTX 20-50W with only around 100 mile since then.
Now I need to ask if anyone with a 2F motor has had this experience before due to a lower engine oil weight used.
I have had the oil pressure drop in the passed due to 90 degrees of OAT but never this low maybe just below the middle line.
Defiantly will be changing the oil to the 20/50 but in the mean time should I d be checking anything else maybe the dizzy?
1st picture shows at speed were the pressure pointer is and the yellow line is were it has always show even on hot days.
2nd picture stopped at light @ 625 RPM
3rd picture stopped at light and really low reading @625 RPM
The compression was taken last year and was prefect.

Stay safe

 

[Tancruiser]

I run straight 30 rotella in mine all year long .

 

[love2fly]

Have you ever seen your pressure gauge this low on a hot day?
With around 100 mile since O/C I am having a hard time believing the oil is the problem, maybe after 3,000 miles.
I may check the pressure gauge sender again but it was new when engine was rebuilt.??????/
Cheers

 

[brian]

These gauges are notoriously inaccurate...however they are consistent.
This gauge is doing exactly what it was intended to do, indicate that something has changed.
You should verify whether or not you actually do have low pressure.
It could be as simple as the sending unit has had enough.

 

[bikersmurf]

If it was me, I’d not worry about it. Having oil pressure drop at idle is quite normal. As your engine ages it’ll do it more... especially with a 10 weight oil that has additives to ack like a 30 weight when hot.

If your distributor wasn’t engaging the oil pump you’d have nothing and it would’t have lasted a week,

Any mechanics care to chime in? Around 1990 or so, Ford replaced the oil gauge in their vehicles with an idiot gauge that showed 3/4 pressure when the 7psi pressure switch showed minimum pressure was reached... because customers freaked and thought something was wrong at idle.
My 7.3 had one... a tired sensor and/or corroded contact made it look like I had no pressure. Keep in mind they often go 1,000,000,000 miles.

 

[love2fly]

I have a PSI pressure indicator gauge installed to the side of the oil filter housing just for this reason and it also reads extremely low. Low time engine from rebuild.
Cheers

 

[Steamer]

I have a PSI pressure indicator gauge installed to the side of the oil filter housing just for this reason and it also reads extremely low. Low time engine from rebuild.
Cheers

If you have a mechanical pressure gauge installed, what are the numbers at high & low rpm?

 

[love2fly]

At the time I just saw high and low on the gauge without taking any numbers down.
Do to other engagements I will have to run a test later tomorrow and get a more precise reading.

 

[RWBeringer4x4]

Now this is for the older style dashboard/gauges but according to the user manual idle pressure was ok as long as it was above “L.” Might be worth seeing if you can find similar for the later gauges to confirm whether or not the same applies.

A lot of these older engines had very little pressure at idle. I have a brand new gen1 350 SBC that runs about 12psi at idle on a hot day. That’s just above the “L” on my stock FJ40 gauge. A lot of these older engines had wide tolerances by modern standards, and pressures were low as a result.

As long as pressure is building with increased RPM you’re probably fine, but I’d hook a pressure gauge up to it with some real numbers and confirm just to be safe.

For what its worth my old 283 SBC had copious bearing clearance toward the end of its life, idled at about 8psi. While this made me nervous, the oil pressure light on old Chevys doesn’t even trigger until pressure drops below 6psi.

I know that none of this translates to your situation directly aside from to say I wouldn’t be hugely worried until I have some real pressure numbers to worry about.

 

[reddingcruiser]

Hey @love2fly, you're just showing off your super-clean dash and cluster

 

[love2fly]

Yes I too have found what you show and a newer illustration, still being an engine under (guessing) 10,000 miles since overhaul one wants to tread lightly until all the facts are available, as the oil being just to thin for this old tractor engine.
Hope tomorrow I can get some more results as the mechanical gauge that is installed. Would of doe it after we got home but I had a duty shift and running late.
Yes oil level dead on.
Well the dash is clean now but usually gets dusty in the summer
Cheers

 

[pb4ugo]

The weight of the oil will effect oil pressure. Obviously a heavier wt will register more psi. If your engine is high mileage or older you may want to run about 40wt. In all my flat tappet engines, newer and older, I run rottella 15-40. It has a slightly high zinc content to help with lubrication at the cam and lifters.

 

[love2fly]

Which Shell Rottella, 15-40, do they have 20-50? That zinc has pretty much been removed from most oils, good for the old engines.
Cheers

 

[brian]

if you are saying you have a fresh(er) rebuild there is no reason you should need heavier oil to see decent pressure.

 

[steffan]

I would think you oil volume would have to be dangerously low for it to affect the pressure... especially at idle. I’ve Only seen it on high g corners in race cars or sustained high rpm pulling motors

 

[AZOKIE]

Did you also check your oil level? My s10 burns oil and when it gets low, the oil pressure will drop a bit at idle but be fine at 'speed'.

FWIW, I run straight 30 weight in my s10.

 

[brian]

One quart down and the S10 will read low oil pressure. Which included going around corners... I forget if it is left turn or right turns... and it doesn't have to be high speed

No noise so I just fill it up with another quart

probably due to the oil spending less time in the pan to cool down, and it running hotter/thinner

 

[love2fly]

Sorry guys for the delay weather here and work has been all bad, anyway had a chance to do a little drive today for abut a whole 25 minutes. Yeah not long but only chance I had.
Well after I got into the driveway the needle was getting low, outside temp was cooler.
Picture one is start up - nice high pressure.
Picture two and three starting to get low
Picture four and five in the driveway getting very low
You can see that the PSI gauge is still shows good pressure compared to th e stock gauge so I am going to change the oil to 20/50 and put a few mile on her as I am believing that this motor does not like 10/30 oil. Also this gauge maybe just getting old.
Would like to find some with a little more zinc maybe straight 30 Wt. That the only conclusion I have right now, and go from that.
I will post the results in a few weeks.

Cheers

 

[love2fly]

sorry last picture Five

 

[whitey45]

20+ psi at idle is plenty!! If this low psi is something new, maybe you have a bearing tolerance issue? Changing oil viscosity is only masking a deeper problem if it continues to stay low?