JTB

iTrader: (23)

Several weeks back I installed a Defi BF oil pressure gauge. I am getting what I consider fairly anticipated readings. When cold it holds 6 bar at idle and falls to 1 bar once completely warmed up. When driving I usually read between 4.5 and 6 bar depending on RPMs.

This weekend I went for a drive in the mountains. This included prolonged pulls in third and fourth gear with fairly high boost readings. When I would come to a stop and idle the car my oil pressure alarm would go off. Looking at the gauge revealed a reading of a varying between .25 and 0 bar. When I would step on the gas the pressure would immediately pick up.

I am assuming that these readings were caused by higher temps than I usually see and the oil flowing more easily due to this.

Anticipating obvious questions.
1) I have checked my oil and it is just past the full mark on the dip stick.
2) I am using Mobil 1 5w30 synthetic – changed by the dealership.
3) No warning lights have come on.
4) The car idles at about 1000 RPM
5) I tapped the oil pressure sender just by the filter in one of the spare holes then was plugged as per articles found on EvoM
6) The car is not running poorly and I am not noticing anything unusual – It is also completely stock.
7) My engine temp gauge never read high or even moved from normal.
8) I do not have an oil temp gauge -- perhaps I need one


My concern is that with this oil pressure, is the turbo receiving the necessary oil to cool it and keep it working correctly – that and all other engine components that like oil such as bearings, etc.

Thanks for the help,

JTB

iTrader: (23)

What sort of readings does everyone else see with their oil pressure gauges?

JTB

iTrader: (23)

bump

LateSleeper

iTrader: (16)

I have the Defi BF oil pressure gauge also. Mine is tapped to a Greddy Oil block sandwiched between the engine and oil filter. Mine stays around .8 KPA at idle when the car is warm. It never falls below .7 KPA when coming to a stop. At high RPM, it reads between 6 and 6.5 KPA near redline. Do you have any idle issues?

JTB

iTrader: (23)

No, the car idles without fluctuation. My readings are the same as yours except after I have been pushing hard and then come to a rest the oil pressure drops.

I wonder if I have my oil temps have just been getting higher than yours?

mttam510

That is suprising! I'd think that you OP would be a bit higher with a thicker oil. I use Redline 10w-30...when cold at 2K it will read damn close to 8 kpa, but after it is warm...it stays @ 6 kpa everywhere, and idle when warm .8 kpa. Where have you picked up the pressure from....where is your line taped into? It could be that the gauge reads low...that would suck! I wouldn't sweat it, it is most likely the gauge.

JTB

iTrader: (23)

I have been doing some research as this has been concerning me. I have gone to a couple of my trusted sources one of which being an ex BWM team race mechanic (as well as many other series). I have learned the following.

1) No or very low oil pressure is bad – especially in a turbo car.
2) Mobil 1 is not very well respected
3) 5w30 is inappropriate -- Valvoline 10w50 or 20w50 or Redline is recommended


BTW – my oil pressure sender is mounted correctly. The only time I experience low pressure is when I have been pushing the car hard. This is temperature related as once the car cools slightly my pressure comes back. – By running the car hard I am referring to 20 minutes of heavy turbo use, not just a 1/4 mile run.

I think that the viscosity of the oil gets so thin once some real heat is put into the engine that my oil pressure is dropping. I guess that my sender could be temperature sensitive but it is unlikely as it still reads consistently once the revs are up from idle.

Questions:
1) Does my theory sound correct?
2) What oil is everyone else using?
3) How does everyone feel about Mobil 1?

Thanks for the input,

mttam510

I diasagree on the oil issue. Maybe go up a step on the oil if you are really rompin on it, and the ambiant temp is above 85 deg. The proper viscosity is mainly for the ring pack on the piston, but also, bearing /journal clearances as well. If you were really breaking down the thermal stability of 50W racing oil (mobil 1), than you would really have a prob. but I do not think that is the case. I was of a bit on my gauge readings. I idle warm @ 1.5kPa and above 3K 6.5 kPa..the car is equiped with Apex gauges. The cooling function of a lubricant within an engine is largely dependant on the volume used, so a larger cooler with bigger lines would add more oil to the system, something that I was thinkin about doing anyway. I am pretty convinced your gauge need calibration, the thing should be pegged on a cool morning when you pull away with 15W50.

Mobil 1 is great oil, no problem there. That is as thick as you'd ever need it to be.

90GSX-03EVO

iTrader: (27)

Mobile 1 10w30
Defi BF oil pressure gauge.

At idle when warm, I see just above 100 kPa. I set my warning at 100 kPa so that if it ever drops below that (like if I keep the car in gear TOO long when comming to a stop, or If I don't give enough throttle on a take-off), I know I have a low oil pressure problem.

At speed when warm, I see above 400 kPa.

At WOT when warm, I see above 600 kPa.

I never drive the car when cold, and I don't pay attention to my gauges when the car is cold, because I usually start the car and then get out and let it warm up while I do something else.

I've driven the car hard for prolonged periods of time and noticed that oil pressure will drop down to right at 100 kPa at idle, but it will never drop down lower than 80 kPa. I'd say that it is because you are running a thinner oil than me. Try switching to Mobil 1 10w30 and see if this solves your problem.

nothere

iTrader: (23)

one thing to consider, oil pressure is an indication of two things really, one is, the pressure against a restriction, ie not an indication of flow so much as an indication of how hard the oil is being pushed against the narrow passageways and bearings of the motor. So you can have high flow and a low pressure reading if you have a sloppy fitting motor. You can also have low volume of oil being pushed hard against a tiny opening and get a high reading.
On the other hand a thick oil being pushed against a tiny opening might read a high pressure but that does not mean the oil is getting inside the bearing as it should.

1, high flow low pressure is possible if the passageways are big.
2, high pressure low flow is possible if the motor is tight.
the extremes of both cases can be ruled out by engine design. Unless you try running a thick oil in a close tolerance motor. I for one would have a little less respect for your BMW mechanic, suggesting 20 50 for a street driven car of modern build.
Mobile 1 10 30 is the suggested motor oil. Other brands including amsoil could be as good or better but in any case the mobile 1 should be plenty good enough.

05-EVO-GSR

iTrader: (16)

When my car is warmed up I get about 10 psi at idle. I do not know about that bar kpa stuff though.

90GSX-03EVO

iTrader: (27)

1 bar = 100 kPa = near 14.5 PSI.

You should be seeing closer to 15 Psi at idle if you are using 10w30.

plokivos

iTrader: (3)

maybe the altitude effected the pressure.

90GSX-03EVO

iTrader: (27)

It shouldn't. Gauges that are installed in cars are read in PSIG, or in kPaG, or BarG (Pounds per square inch - gauge, kilopascal - gauge, Bar - gauge). that means they measure the pressure of the installed system, rather than pressure in relation to ambient. It's the same reason that a boost gauge reads zero PSI, kPa, or Bar when the car is turned off, rather than 14.5 PSI, 100 kPa, or 1 Bar.......granted all cars being tested at sea level. Atmospheric pressure is not a consideration when talking about the gauges that are on the market for cars.

90GSX-03EVO

iTrader: (27)

When I drive the car with the RPM's staying over 5000 for a sustained period of time, this is usually the type of indication that I see on my oil pressure gauge.