hi i have a 1993 w250 with 201,xxx miles and i have been noticing that when the truck is at operating temperature, the oil pressure drops down to the first line on the stock oil pressure guage. it is due in 1,000 miles for a oil change but when its cold the pressure is on 3rd line. just seems like to big of a change for me to not worry. also the oil level is not low and i do not have any blow by.

 

when it was hot out here the fuel would be so thin it would drop the idle by 150RPM and it would make my oil light flicker then it would come up as you say if you hit the throttle

i would not worry about it i did and installed an aftermarket gauge with numbers and it would go from 30psi at idle to 60-70 at freeway speeds

 

Its your pressure sender. The vibrations kill it and cause weird readings.

 

Sounds like typical readings to me. They don't put pressure numbers on the stock gauge face for a reason, it's good for seeing trends but you need a real gauge on it to know if it's at good levels or not.

 

My stock gauge read low like yours for the whole 2 years I've had it. Recently, the oil light would start to come on like yours. I did an oil change, and at the same time remembered I bought some VE pump parts. There's a cushioning spring on the VE throttle shaft that wears and eventually breaks. As it wears, your zero-throttle position is lowered along with idle rpm. I changed the spring and my idle was noticeably higher.

The following day I put in a mechanical gauge and got 53 psi cold, and 49 psi hot warm Not bad for 392,000km!


The last picture is my '93 that had an even worse spring.