Muerde

Hi guys

I have unusually high Oil pressure and would like to know what steps can be taken to reduce the oil pressure? I have no idea if I have a standard oil pump or not... any help of advice would be great..

Like wheres the oil pump, thats the standard one look like?

Thinking a Impreza Haynes book might be required...

Cheers in advance

Ian

Ooh guess its important I ahve a 01 Bugeye WRX...

MaDaSS

What would be your oil pressure reading for you to think it is too high?
From cold, like overnight, mine is upto 7 bar.
Then when running over around 2500 rpm my pressure is 6 bar.
3 bar on tickover when warm, and higher on tickover when cold.
So what are your readings, before you start taking things to bits.

Plums!

Oil viscocity can have a big effect on oil pressures....

The thicker the oil the higher the pressure....

What oil are you running with? Check that it isn't overfilled This can also lead too high pressure extremely important and can cause terminal damage to the internals and it happens suprising too often at garages

Also if oil pressure is really too high get it checked out sooner rather than later!

Plums...

Muerde

The Pressure is at 100PSI + cold the once its very hot drops to about 99PSI while running at about 2500rpm+
It settles nicely at idle at about 25PSI.

Its been to the garage had fully synthetic oil 4.5 litres and a new filter... hopefully the 01 newage takes 4.5 litres....

Plums!

o.k. I'm running 5W-50 Mobil 1 in mine
Cold I get 6-7 bar Which is 88-100PSI
about 6 bar at 2500rpms 88PSI
Fully Warm idle 2.3-2.6 bar which is 33-38PSI

If your oil is thicker say 10W-50 or more then the oil pressure will be higher... or the lower if using a thinner oil say 0W-30 (Although thin oils are frowned upon on this forum!), I use 5W as winters here can get pretty cold!

Try to find out which oil you have and always keep an eye on your oil level (These engines don't like to be overfilled!)


Cheers,

Paul

P.S. try doing a search on scoobynet for oil pressures I'm sure you'll find more comparisons...

stockcar

those pressure are bout right, if anything a little low on idle, but fine..............

why did you think it was too much??

alyn

Muerde

100Psi is far far more than it shoudl be used to race a formual for and ran that at about 15Psi more pressure certainly does not mean more speed, infact I think running 100psi will be wiping out BHP probably as much as 5-8 BHP to keep the oil pressure this high.

I am going to get mine to hit a max of 80Psi, cold I can handle 100psi, warm I am just destroying my engine as are all the other scooby drivers who think 100psi is normal.

I could be wrong, and I guess I will take this to my local Subaru garage now to see what they can do.. will keep you updated.

Shark Man

I wouldn't let you worry you too much. Unless your blowing oil seals etc.

Although your right in saying high pressure is a waste (IIRC the relief valve opens at about 70psi, so anything above this just wastes oil flow back into the pump inlet.

Obviously oil viscosity does have an impact - especially at this time of year.

Personally I would sway away from 10w-60 or 15w-50 oils. And only use 10w-50 if the car was getting hammered on a regular basis.

What are you using to measure the pressure? Obviously bear in mind that the guage itself could be faulty (or the connections to it - if electric).

Slowboy Racing

I wouldn’t really want my oil pressure at 100psi 2500 rpm when hot, i would suggest changing the oil to a lighter grade.

I see around 85 psi at 8500 rpm and 25-30 psi on idle, with a high flow pump and light grade oil.

jasonius

iTrader: (1)

4.5 ltrs could be too much, depends on how well is was drained.

When I drain my 05 wrx for around 30 mins (warm/hot oil) and if I pre fill filter (properly) I put in JUST over 4 ltrs to get a cold level halfway between low/full. Anything more and it's overfilled IMHO..!

If you're still running TMIC check to see if there's any oil residue inside (that's provided you're running std PVC system) this is a sure sign of overfilling ..

Obviously there's the dipstick, but a lot of scoob owners struggle to get a proper measure..!

rigga

iTrader: (4)

These are normal readings that alot of guys see on here,me included..... what guages do you run,delfis or cheap ones?......... from your previous postings on this i still doubt you have a problem.

James Neill

iTrader: (1)

Normal readings. Mine is over 100 psi when cold. 90-95 psi when warm and 30 psi at idle.

GazJenno

My oil pressure went from 6 bar (approx 88psi) warm cruise to 7 bar (approx 102psi) when I overfilled it slightly... drained abit and it has gone back down to 6 bar again and thats with Motul 15w50. Maybe slightly over filled yours?

Slowboy Racing

It’s not a problem as such but for some not ideal. The lighter the oil the better the oil will flow and lubricate the motor and the result of this is lower oil pressure to a point.

The main reason you see higher oil pressure is due to the oil weight been heavier. The oil pump will struggle to circulate the same amount of oil as the lighter weight oils and the end result is generally a reduced flow and increased pressure. Bear in mind a rule of thumb is 10 psi/1000 RMP look at most engine manufactures and this will more or less apply. You will also see minimum oil pressure at certain rpm for example Subaru recommend around a minimum 55 psi iirc at 5500RPM. That’s half what some of you guys are seeing at double the RPM. I am not saying this is something to aim for just an example of a minimum pressure as I would expect most to see around 70-80 psi at 5500+ using 10/40

if you’re seeing 100psi at 3000rmp on a hot motor this tells me the oil is too heavy or there is a problem with the pressure relief valve. You’re not getting any benefit from this in fact I think your reducing flow as said above and also robbing the motor of bhp due to friction losses as its taking more energy to pump the oil around the motor.

If however your running the car on the track with a heavy 15/50 or 10/60 its quite possible to see these pressures but bear in mind the oil will see much higher temps running most of the day on WOT, most road cars wont see these oil temps so to me it defeats the purpose of running the oil if all it does is reduce flow and adds to friction losses.

I have spent considerable time trying different pumps, spring tensions shim sizes and oil weights to get my oil pressure where I am happy where I have optimum flow and pressure at through the Rpm. I don’t believe running heavy motor sport oil in a fast road car really benefits, unless the motor has been built with the intention of using specific oil like Subaru has done or it is seeing exceptionally high oil temps in which case i would fit a cooler.


Just me ten pence worth.

Plums!

Un-ink are you sure about this statement.....
Bear in mind a rule of thumb is 10 psi/1000 RMP look at most engine manufactures and this will more or less apply.

If this is really the case then at idle I would have 7 psi and at 7k rpms I would have only 70psi.... which obviously I don't?

Have I missunderstood something?

Plums....