Sorry everyone another "Oil pressure" question

[ordwood]

So I have a 4.0L Speed Six in a Cerbera and have always been a little concerned about low oil pressure when the engine is hot and just ticking over so at the last service I had the oil changed from the Mobil 1 0W-40 to a fully synthetic 10W-40 which was suggested would help the problem.

Well after a few months driving I'm still a little concerned so wanted to ask everyone's advice as to what it normal.

So here's some of the data I've managed to copy down.

Starting from cold 53psi at 800 rpm
30mph. 26psi at 1400rpm and temp 77deg
40mph. 30psi at 1500rpm and temp 79deg
50mph. 42psi at 1800 rpm and temp 77deg
60mph. 47psi at 2500rpm and temp 77deg
70mph. 50psi at 3000rpm and temp 78deg

But here's the troubling one:
Stationary 12psi at 800rpm and temp 80deg

Now if this is normal (I sincerely hope it is) then I can stop worrying so if anyone can give me some input from their own experience I'd really appreciate it.

Many thanks in advance

[Englishman]

Yes, quite normal, in fact very good!

On a really hot day, when stuck in traffic, I've seen the oil pressure drop into single digits in a number of cars, again quite normal.

I did have a warning message come up at 4psi in my first Sag, but after talking to a number of experts I ensured the car was subsequently serviced using 10W40 semi synthetic oil and it never dropped that low again.

[NCE 61]

Similar figures to my Tuscan, a bit higher when cold i.e 60 psi , but 10 to 12 psi when hot using 5W40 oil.

[m4tti]

It's the nature of the head design. Replace the head and it goes away...

1k idle... 93 c oil temp

[ginkent]

ordwood said:

So I have a 4.0L Speed Six in a Cerbera and have always been a little concerned about low oil pressure when the engine is hot and just ticking over so at the last service I had the oil changed from the Mobil 1 0W-40 to a fully synthetic 10W-40 which was suggested would help the problem.

Well after a few months driving I'm still a little concerned so wanted to ask everyone's advice as to what it normal.

So here's some of the data I've managed to copy down.

Starting from cold 53psi at 800 rpm
30mph. 26psi at 1400rpm and temp 77deg
40mph. 30psi at 1500rpm and temp 79deg
50mph. 42psi at 1800 rpm and temp 77deg
60mph. 47psi at 2500rpm and temp 77deg
70mph. 50psi at 3000rpm and temp 78deg

But here's the troubling one:
Stationary 12psi at 800rpm and temp 80deg

Now if this is normal (I sincerely hope it is) then I can stop worrying so if anyone can give me some input from their own experience I'd really appreciate it.

Many thanks in advance

My 4L cerb sp6 is similar with Mobil1. Plugged into an ecu display I have only ever seen the psi drop as low as 14 on a hot day. It usually is 15-16. If it went into single figures i would sh*t myself

[Konrod]

I had mine rebuilt by Dom, and had the same question about oil pressure when very hot. His comment was the oil pressure unit under the airbox is not very accurate and varies, so if I'm seeing any oil pressure at all at hot tickover then I'm fine.

30k miles later with lots of time in queues and it looks like he's right.................

Make sure thought that the radiator fans are working. The oil cooler is oil to water, so relies upon the cooling system water to cool the oil as well (actually stabilise the oil temperature, not cool it).

[brownspeed]

Sounds fine.
from Graham Varleys webpage -.......Oil Pressure When I first had delivery of my car and when very hot, the oil warning would come on down at 4 psi at idle. There is various theory's on this but I sorted mine by having a more healthy engine idle when hot of 900-950rpm(the car should idle from cold on its own). Loads of factors on this one like oil viscosity vs temperature etc. With fresh Mobil 1 5W/40 mine runs on idle ;- 20deg 65 psi , 30deg 50psi, 40degC 35psi, 65degC 25psi................."

http://www.varleyhyd.com/FJ062.asp#Fault%20codes

[ordwood]

m4tti said:

It's the nature of the head design. Replace the head and it goes away...

1k idle... 93 c oil temp

Replace the head with what ?

An FFF one or perhaps an Ls lump ;-)

[ordwood]

Thanks Guys, you've made me feel a lot happier.
Will still keep an eye on it but doesn't sound like I have anything to worry about, well at the moment.
Cheers

[m4tti]

ordwood said:

Replace the head with what ?

An FFF one or perhaps an Ls lump ;-)

FFF

Although having recently seen a ls7 transplant in progress it doesn't look as out of place as I thought it would. Never thought I'd say it but part of me thought it looked pretty cool.

[potash4]

Very normal. When mine is really hot it often drops to 8psi at 750rpm.

[mungral]

being new to the S6 (2002 Tamora, 45,000 km) the horror stories of head rebuilds and poor oil system made me particularly conscious of oil pressure. Had my first run out last weekend and was surprised/concerned to see a high oil pressure warning on starting and 'oil sender' caption on the display. The oil never got particularly warm, 65º, but it was mostly motorway cruising. However oil pressure was around 20-25 psi at idle and up to 70 psi at cruising revs (3,500).

Is high pressure to be worried about on these things or do i just suspect a transducer problem albeit opposite to most people's?

[Englishman]

I've seen 60psi @2500rpm when cold, but does look as if your indicated oil pressure is about 10 to 20psi too high. Faulty sender is most likely culprit and the first thing to swap.

Second thought is an incorrect specification or badly fitted pressure release spring.

Edited by Englishman on Monday 24th July 09:15

[astonman]

Use Castrol Edge 10/60.

[robsco]

My T350 dropped to 3psi in the baking heat of the south of France whilst sat in traffic!! 35 degree heat and oil at its thinnest. I held the idle up to 1200rpm or so and it would sit around 12-15psi at that. Just the nature of the head design.

[astonman]

What oil were you using?
Edge 10/60 works like viagra for low oil pressure.