I switched to Delvac on Saturday. When I start the truck cold the pressure is 70 (used to be 90-100). When it gets to operating temp and Im sitting at a light (61 degree day) it drops to 20psi maybe lower. This seems very low and Im really worried. Whats everyone else here think? I get 2 3/4ths bars on the gauge. The guage is 30 psi per 4 marks. So my calculator tells me thats 20.6 psi at hot idle.

I switched over to Delvac 1 at 1200 miles and my gauge reads the same as yours. It seems low compared to the higher oil pressure of the previous years. I've read posts on another forum that indicate it's normal. I haven't had any oil related failures and I have 23k on the truck so far.

I switched to Delvac on Saturday. When I start the truck cold the pressure is 70 (used to be 90-100). When it gets to operating temp and Im sitting at a light (61 degree day) it drops to 20psi maybe lower. This seems very low and Im really worried. Whats everyone else here think? I get 2 3/4ths bars on the gauge. The guage is 30 psi per 4 marks. So my calculator tells me thats 20.6 psi at hot idle.

IMHO,70 PSI cold is good for better oil flow and 20psi hot idle is OK as well. What is your pressure hot at 2000 RPM (65MPH)?

Problemchild, I just did my seasonal swap to synthetic last weekend (Rotella-T 5W40). JPblock has it right, the synthetic will show lower pressure at idle, but at speed will be within 5 to 10 pounds of dino readings, which is most important. It's also very nice to cold start and see that pressure is not "through the roof." The increased film strength and flow capabilities of the synthetic provide greater protection than dino oil, even if pressures look a little scary.

Someone replied to a similar question over at pickuptruck.com. The poster stated that minimum oil pressure should be over 14 PSI at idle and 62 PSI at 1800 RPM. Hopefully Eric or others can verify this.


Also be aware that the in dash oil pressure guages are known not to be very accurate. So are the temp guages.

Heres my current pressures with delvac.
Cold start its 70+
1800 rpms hot its 65+
Idle rpms hot its about 20 +/- 2
Warm idle its 30+

What we need is a delvac thats 10-40.
That would make the hot idle 30+

Heres my current pressures with delvac.
Cold start its 70+
1800 rpms hot its 65+
Idle rpms hot its about 20 +/- 2
Warm idle its 30+



I am using Shell Rotella Synthetic 5W-40 and getting the same pressure readings.


The thing I like best is the almost instant pressure readings when starting cold. It would take several seconds to register pressure with the 15W-40.

I had mine checked at the dealer for this same issue. They put a manual guage on and it read 18psi hot. They checked the three other new d-max trucks on the lot and they were all the same as mine. They say it's normal.

When I switched from Delvac 1300 15W-40 to Delvac 1 5W-40 my oil pressure actually increased. This does not make sense, but is true. Any ideas why? http://www.dieselplace.com/forum/smileys/Confused.gif

Looks the same as mine, talked to delarship and they told it was norm! But it did drop after the first change?Edited by: Atrzes

Hmmm, an increase with synthetic is not normal, Duckdog. Did you change anything else when you changed oil? Filter? On oil viscosity and "slickness" alone the pressure should have gone down with syn. The stock oil pressure gauges are notoriously inaccurate - could just be the gauge/sender, though.

Idle Chatter,


This is a great mystery to me, nothing else was changed when I did the oil. The old oil looked normal, and the level was normal. There was no sign of fuel or coolant contamination. I used the same Baldwin filter #B1441. I do not use any oil addatives, and my truck is stock. The gauge seems to function properly, even if the numbers are not exact. The truck seems to run good, no problems there. I really expected the oil pressure to drop with the synthetic.


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