High Oil Press Should I be Considering a Lower Viscosity Oil?

[wagonboy]

Hello,
I seem to be paying more attention to the oil pressure gauge than the tach.

I've read a number of threads on this topic. Normal oil pressure when engine is warm should be 10 or 15 psi/1000 rpm. Should I be concerned that my pressure is roughly double that? I hit 60psi on the gauge at 2600rpm when the temp is 180. These days, the engine temp doesn't get much past 180 (ambient temps in the evening are in the 50-55 degree range).

During the summer when it was warmer, the pressure always seemed higher than I would have expected. My greatest worry is that the engine isn't getting enough oil flow. I have really babied her and never go much beyond 3000 rpm until she's good and warm but even still, I'm worried. I check the oil level after nearly every run. It's currently at about halfway between min and max on the dip stick - this really shouldn't have a bearing on pressure levels from what I understand.

I have Brad Pen 20/50 in it now but I'm thinking I should try their 15/40 variety. Would be interested to hear any words of advice.

Thanks in advance.
Marc

[advtracing]

You advise half way on the dip stick ? Have you checked the oil level gauge when stationary on a level surface at running temp? As the dip stick is not the best way to check .
I have just done my oil on a new car today , the oil level was set based on the dip stick by the last owner , from this the oil presure was high when purchused , when emptying the oil today i found it over full by 2 ltrs .....
Changed to brad penn as usual , set oil level at running temp on flat sutface by dash gauge at half mark and perfect pressure .

[chris_seven]

It may be useful to try to find information regarding the viscosity/emperature curve of the oils you are using.

If the prssure high because the temperature is low then you could have other issues such as cam scuffing or other issues due to incomplete oil films.

If the temperature is low then I would try to find out why you seem to have lots of cooling.

If the temp is correct then why is the pressure high/

Once you have the answers you can amke a decision about the oil but I think without the data you could mask one problem with another and end up with a long term issue.

Oil temp needs to be within a few degrees of 90degC.

[jameshtaylor]

Before doing all this swap in someone else's oil pressure sender. Probably that's your only problem. If that doesn't give you a decent result, swap in another gauge and see what you get.

[porschegal]

we have a low pressure problem right now. we have eliminated the guage as kevin of North hollywood speedometer checked out our gauge. so i run on the freeway and the guage is near 0 or just a hair above zero, at warm at freeway. I am going to have the hubby change the oil pressure sending unit. wich is about 2 inches behind the flywheel and about right of the MFI unit. People in the past has changed the spring of the relieve valve. if the Relieve valve is weak. that could be a the culprit. generaly 1k rpm = 1bar. but it says in the manual it varies. if you want more pressure you can shimm the bolt or plug with 6mm washers to get more pressure..to get less you cut some turns. but i would rather change the whole spring. i sell em btw.

I would eliminate the the gauge and sending unit . you may want to hook up a oil pressure guage and see if your running 15psi at idle? then go from there..


best of luck

Porschegal " marge"

[wagonboy]

You advise half way on the dip stick ? Have you checked the oil level gauge when stationary on a level surface at running temp? As the dip stick is not the best way to check .

Personally I wouldn't depend on the gauge to measure oil level. Mine reads low all the time yet I had oil sitting at Max on the stick 1500 miles ago. It slowly dropped on the stick to where it's half way now and yet the gauge still reads the same.

The engine was rebuilt 1900 miles ago as were the gauges. Although I feel I need to have the oil level gauge recalibrated, all gauges were refurbished by North Hollywood. They are the experts and do good work so I'm figuring blaming the gauges is one of the last things on my mind. I'll check the sending unit first. Chris, your note regarding incomplete oil films... I would imagine that with just 1900 miles on the engine and even less on the oil in the tank, I still have enough ZDDP in the oil to prevent scuffing issues. My original plan was to add some oil as the level dropped on the stick then change the oil/filter each spring. With the higher pressure readings on the gauge and given the climate I'm living in, 15/40 grade might suit better. First it would be less molasses-like when cold and second, the increased flow of the slightly thinner oil should, in theory, result in a drop in pressure.

As the engine is still relatively "new" since the rebuild, might the higher pressure be partly the result of lack of break-in mileage? 180 degrees is lower than the 200 I was running during the hotter summer months but it still seems to be within the generally accepted range. Now everyone's heard of oil coolers, has anyone ever heard of someone installing an oil heater in their road car? lol. BTW, my car does not have an oil cooler.
Regards,

[porschegal]

our 2.2 and 2.4 engines were design to take SAE 30 . with the new oil products of 20w-50 . is already thin . i wish there was 30w-50 . if you go 15w your whole engine will start to leak all over the place.

2cents
Porschegal "marge"

[gled49]

first, does the oil press gauge; example 0-140 psi, match the senders 0-10 markings. second, you need to give more rebuild info; example, were the case halves machined and a new standard line bore done, as this has been known raise oil pressure a lot. If your oil pressure is high don't run 20/50, run 15/40, it won't cause any oil leaks. gled

[wagonboy]

first, does the oil press gauge; example 0-140 psi, match the senders 0-10 markings. second, you need to give more rebuild info; example, were the case halves machined and a new standard line bore done, as this has been known raise oil pressure a lot. If your oil pressure is high don't run 20/50, run 15/40, it won't cause any oil leaks. gled

The short answer is that I don't know for sure. The engine work was contracted out to Supertech. I am still waiting to receive the detail on restoration work including engine. What I do know is I have a '77 mag case (as per numbers 911/85 6275216). The engine is built using Nickasil liners, original MFI modified for 2.7RS spec and 8.5:1 comp.
Assuming for a moment that the case halves were machined and a new standard line bore done as suggested, would the higher compression resulting from this be a cause for concern? What would the fix for this be? Adjust the relief valve?
Thanks again for the feedback.

[gled49]

not higher compression, higher oil pressure. run thinner oil, and try to reduce pressure with mods to pressure relief. I plunge the cap deeper, but have never cut coils out of the spring, Henry should be able to help you solve the problem. gled