low oil pressure

[angel]

for about a month my oil pressure has been under 4 on the oil pressure gage. Previous to this it was always just above the 4. This is during normal driving. At idol it is almost hitting the bottom of the gage. I have checked the levels, and I only had the oil and filter changed two months ago (mobile 1 ). I have booked her in for a service this week, but after a recent bad and very expensive experience, I want opinions from you guys first, before the mechanic gives me his version.

[(B1) MR_fanny]

my oil pressure dropped from what used to be half mark warmed up to 1/4 mark idle after changing to lighter castrol formula r 5-40w. i figure its just cause the oil is lighter so pressure is different. under load i think it goes up to the half mark. the old oil that was in it must have been thick as it never seemed to move even when it was on load. does this sound right?? can anyone shed some light??

[wrxhoon]

it will depend on the opil u use and the temp of the oil .

thinner oil lower pressure hot oil =lower pressure too. dont forget the oil doesnt get hot quick like the coolant it may take half hour driving to get to say 120 . u may have a crook oil sender or crook gauge . pressure is not tha important volume is as long as u have oil pressure it will be ok

[Demon Dave]

I had a similar problem happen on my R33 - after much worry it turned out to be a faulty pressure sensor guage - apparently a common fault on RB engines...

[Jetdat]

well the factory oil pressure gauges/sensors are very dodgy...they are not very accurate or consistent...

but its better if you get the oil pressure tested to be safe, or even instal an aftermarket oil gauge...

[Ronin 09]

RB oil pressure sensors/senders/gauges = dodgy. Get a good aftermarket one if you are worried. I have a Greddy oil pressure gauge - when the car has been running a while the nissan gauges cracks the poos and wont really read higher than 2 or 3. It is simply not reading accurately. I've had no problems with the Greddy unit.

[antuanstylar]

if there was a problem with oil pressure or starving the engine of oil wouldnt the engine overheat also?

[wrxhoon]

its not just rb gauges that dont read accurate most stock gauges dont . dont forget most cars dont have any at all just a warning light that goes on when pressure drops to about 5 -7 psi .

the gauge is not there to tell u when u r low on oil it wont do that , driving easy it will pick up oil even if u have 1 - 2 lts in the sump . the dip stick wont show anything if it drops to 3 lts . between min and max on the dip stick its about .8 lt ( rb25det,1lt rb25de ). the gauge is there just in case ur oil pump stuffs up , if u r contantly looking at it u'll se it drop and may save ur engine , but u'll hear the bearings knock as soon as pressure drops if the sound system is not to high lol !!!in both cases the big end bearings will pick up a little ( the gauge reacts slowly ) but will be ok if u stop the engine quick . if u install a mechanical gauge ( most accurate ) they all use plastic tubes these days the plastic tube can come out when the oil gets very hot , u loose oil and bingo the end of ur engine .

if u r worried have the pressure checked and if u want install a aftermarket gauge but remember its only a guide and u dont need huge pressures as long as the volume is there u r fine .

standard rb 25det pressure is : idling ( 650 rpm )1 kg/cm2, 2000 rpm 3.5 and 6000 5.6 .thats when oil is hot , if u dont have a temp oil gauge after normal driving for about half an hour , and using normal spec oil , thinner oil =lower pr thicker oil =higher .

i dont know at what pressure the release valve will open but on my gtr it opens at about 6kg/cm2 , i think the rb25det opens a little higher .

the rb 26 pressure at 6000 is lower as well 4.6 and 3 at 2000 which goes to show u that u dont need high pressure, volume is more important .

[wrxhoon]

by the time u see the coolant gauge go up cause u got no oil pressure ur engine has probably spun all the big ends and the crank is ready for scrap . u will hear the big ends knock as soon as pressure drops . when ur big ends have a big clearence ( worn say 1-2 thousants ) when u first start the engine u'll hear the big end bearings a little for a few seconds another reason u dont rev the eng when u first start . when u do an oil change u may notice the same thing if u dont fill the oil filter with oil before u put on ( imposible in the skyline pos in some cars that the filter is upright .

[Jase]

asked exactly the same question - apparently the sensor is very unreliable

mine changes everytime I start the car changes from 4 to 2 to 1

asked my mechanic he said this is common in skylines

[JimX]

Just to go against the trend, mine is perfectly fine It reads around 6 when cold and drops to around 3 when warm. At idle that is. When driving it goes up.

[wrxhoon]

same here jimx my r33 gtr reads 3 at idle and about 6 at 2500 rpm