Oil pressure below 1/4

[scottm]

At highway speed, 2000 rpm, the oil pressure is just above 1/4. It drops a hair below 1/4 at hot idle. I've not seen it reach 1/2. The dealer just changed the oil. Perhaps the gauge is wrong? Wishful thinking? It's going back to the dealer next week for the torque converter, good chance to get it looked at.

[DMX84]

I don’t like to base actual pressure on a factory gauge……it’s just for reference. If our LC runs normally at 1/2 and now it’s running at 1/4 than you can base some concern, otherwise you don’t have anything to go on, because it’s not that accurate. I would get a real gauge even if it just tempary to see what pressure your 1/4 scale reading is.
DMX

[scottm]

I mentioned my concern when it was in this week, they didn't say anything about it. I think the dealer should be able to check the pressure, maybe even correct the gage if it's off. If nothing else, it'd document an oil pressure issue when I first bought it, in case something goes wrong before the 100,000-mile warranty expires.

[cruiser100]

Originally Posted by DMX84

I don’t like to base actual pressure on a factory gauge……it’s just for reference. If our LC runs normally at 1/2 and now it’s running at 1/4 than you can base some concern, otherwise you don’t have anything to go on, because it’s not that accurate. I would get a real gauge even if it just tempary to see what pressure your 1/4 scale reading is.
DMX

x2. The stock gauge is not very accurate at all. The only thing it tells you, IMHO, is that you 'have' oil pressure. You'll need to get a good mechanical gauge to get a good reading and determine if you have an issue or not.

[NMuzj100]

These low readings are normal. If the oil level is correct then there is no reason to worry.

[scottm]

Originally Posted by NMuzj100

These low readings are normal. If the oil level is correct then there is no reason to worry.

My manual says "normal" is above 1/4-scale, so this worries me. Fresh oil has always yielded me higher pressures in other vehicles, so I'm wondering what the pressure will be like in 5k. I'm already seeing it drop in the first few 100 miles. Yes, factory oil pressure gauges are notoriously innacurate and designed to stay centered in the "normal" range while the real pressure fluctuates. But they are reasonably similar from truck to truck, and a significantly lower reading than other similar trucks is something that concerns me.

I've hooked up mechanical gauges on other vehicles, does anyone know if there's a convenient port for this on the 100? The truck goes back to the dealer on Wednesday for a new torque converter, I'll ask them to check the pressure with a mechanical gauge.

[NMuzj100]

If you search on the forum you'll find that several others have had the same readings on the dash gauge, checked with a mechanical gauge and found they had pressures within the normal range. At highway speeds it should get to the 1/4 mark.

The mechanical gauge is attached in place of the oil pressure switch right behind the oil filter. The oil pressure is only supposed to be above 4.3 psi at idle per the FSM (LU-1). At 3,000 rpm the range is 43-85 psi. Use locktite when reinstalling the switch.

At 5k your oil will still be new in the UZ engine.

[scottm]

Thanks NM, that's the info I was looking for. I thought I searched before posting, now I see a couple old threads on this. I've got a bunch of questions at once about this truck.

I'll have them check the pressure anyway, they should do it for free right now. I'll feel better, and have a good answer to anyone who asks about it, like if I ever sell it.

It'll soon have Rotella T Synthetic in it, once the dealer is done repairing stuff.

[Boston Mangler]

For what its worth:

Just bought a 99

When purchased, needle was at about 1/8 at idle and about 3/8 around 2500rpm

Just got done swapping over to Mobil 1 and its 3/8 at idle and between 1/2 and 3/4 around 2500rpm

My .02

[scottm]

Wow, what weight?

[Boston Mangler]

Originally Posted by scottm

Wow, what weight?

Mobil 1 5w-30

[BOGH]

My gauge was 1/4 idle cold start and a little bit when was hot and at 200-2500 RPM a little bit bellow 1/2 measureted at -35C(-31F) + wind chill and now i have around 3mm more at 0C (32F).

I use only Mobil 1 5W 30 and in the cold time Mobil 1 0W30 on my cars.

Bog

[vak01]

Have a 99 also. VERY similar results on the OEM dash gauge. Also using Mobil 1 5W30

Originally Posted by Boston Mangler

For what its worth:

Just bought a 99

When purchased, needle was at about 1/8 at idle and about 3/8 around 2500rpm

Just got done swapping over to Mobil 1 and its 3/8 at idle and between 1/2 and 3/4 around 2500rpm

My .02