Variabler Oil Pressure Problem (different than usual)
 

I know there have been a fair number of posts on oil pressure problems, but my situation is different than usual and I'm in a bit of a bind in terms of my ability to use facilities & time to fix things, so...

Essentially the oil pressure is variable at different times. On one journey it may read only ever so slightly low (I know what proper is). On another it will read a tad below 60psi. Another it will be in the 45psi range. Sometimes on longer trips it might start low at the lowest of the three scenarios and by the end be at the high end. Other times it might start high and end up low. While it is variable I've never actually noticed it dropping or rising at an unexpected time. I never see it fluctuating when I'm driving. (other than when I've just started to drive around)

There do not appear to be any oil leaks. The situation has been happening for a while so I've been able to monitor the oil consumption and it's fine. The sender is fine.

So what things should I look at first? Please give a quick explaination of what I should be looking for in each of the checks. (just so I have a basic understanding of the purpose of the check, etc. and can find out more info if I need to)

Thanks.

PS. I've been using a lean pre-mix ratio to try compensate for the sub-normal oil pressure.

In case you care (which no one probably does), I'm going to replace the oil pressure control valve first. Don't know if that's logical...

Try the gauge itself. You would not believe how poorly that thing works when compared to a mechanical gauge.

Oil pressure is also dependent on viscosity and the air temp.

On colder days I have seen the oil cooler thermostat stay closed long after the engine water temp has warmed to operating range. When this happens your oil pressure may stay lower.

But I agree with Kevin, the stock gauge is not terrible accurate. It too can be less accurate when cold.

I think the guage works, but to be 100% I already have a gauge and the proper fittings to attach the sender that I was planning on putting in tomorrow. I have little confidence that is the problem. The deviance in pressures are too great given changes during constant temps and oil.

Do you think I should be checking/replacing the oil cooler thermostat first?

I would check the oil pressure with a real gauge first, then go from there.