RS2 - Oil Warning Light at Idle - 1.0 bar

**rustybullethole** · 20 March 2022, 11:11

Could be a weak oil pressure relief valve, or the valve slightly off of its seat, I.e. not closing fully. Could be slightly worn bearings.

**varia** · 20 March 2022, 15:53

I would make sure the car has the proper type of engine oil then check the pressure with a (decent) mechanical gauge).

**K Simmonds** · 20 March 2022, 16:26

As above, confirm what the oil pressure is doing with a mechanical gauge then go from there.

**Tractor Dave** · 20 March 2022, 18:47

Yes, agree with above. What grade oil (I think you call it weight over there) are you using? These engines don't like thin oil.

**Bimmerod** · 20 March 2022, 19:29

Appreciate the responses, I will look into getting a mechanical gauge to see exactly what's going on. Where is the best place to hook that up? I imagine in one of those two sensor holes?

I know there has been a lot of discussion about "oil" based on the number of threads I see. Just curious if there has been a consensus on what grade to use for spirited everyday driving? The engine was refreshed less than 5k ago, complete teardown/rebuild and haven't given any issues up to this point. So is it really necessary to use 10w-50 if the motor is fresh?

PS- Looking at the notes it appears they used 5w-40 oil for the last change.

Pretty sure those two oil sensors were replaced "just because" since they were going through everything.

What I can't figure out is what is telling to Oil Warning Light to come on @1k at idle? If the F22 is set to go off at 0.3 bar and the F1 at anything below 1.8 bar above 2k then it's strange. What should the normal idle RPM be? Is 800-850 too low? Because if I raise the RPM's a little the OP goes right up and the warning light goes away.

Getting 10w-50 here in the states is looking to be a challenge as no one really makes that grade.

Let me know your thoughts

**Tractor Dave** · 20 March 2022, 19:49

5w40 is a bit thin. Can you get 10w40 or even 15w40?
Yes, put the oil gauge on the smaller oil sensor.
Try removing the oil temp sender under the block and clean the oil relief valve. Mine had black carbon grit in it after engine rebuild.

**K Simmonds** · 20 March 2022, 20:13

As you say hook the gauge up to the one of the two sensor holes, whichever you can get at the best.

5w-40 could be a touch on the thin side depending on ambient temperature, kinda depends if your in Texas or Minnesota, but even then it should really be okay if it's decent oil. What's your oil temperature gauge saying when you've given the car a good spirted run and what's the ambient cold start temp range?

10w-40 should be fine just about everywhere but don't know how easy that is to get in the USA.

My RS2+ spec 3B seemed happiest (very consistent pressure readings & quiet engine) running on Fuchs Titan 20w-50, I'd just be sure to take it easy until the oil was up to temp, but it would get a dam good thrashing once warm.

Am running the same oil in my RS2 with no issue's, I just let it warm up before giving it any serious boost, doesn't take long say five min's in the summer, ten in the winter. That said it doesn't really get that cold over here, rarely below -5C / 20F, normally between 5C and 25C or 40F and 75F in freedom units. It would probably be a bit on the thick side for the more northern states.

Can you try another F22? As it could simply be this playing up and triggering the warning when it shouldn't as well as giving inaccurate readings under some conditions. Even if it's been replaced it could be a faulty unit.

Otherwise perhaps it could be the relief valve as mentioned above, very much doubt it's the shells if the engine is running smoothly and quietly.

**Bimmerod** · 20 March 2022, 20:35

Originally posted by Tractor Dave

5w40 is a bit thin. Can you get 10w40 or even 15w40?
Yes, put the oil gauge on the smaller oil sensor.
Try removing the oil temp sender under the block and clean the oil relief valve. Mine had black carbon grit in it after engine rebuild.

I can get this but it seems like everything labeled 15w-40 is for "Diesel" applications - https://rotella.shell.com/en_us/prod...synthetic.html

This is the oil relief valve / temp sender you are talking about ? -
oil pump.JPG
Thanks

**Bimmerod** · 20 March 2022, 20:48

Originally posted by K Simmonds

As you say hook the gauge up to the one of the two sensor holes, whichever you can get at the best.

5w-40 could be a touch on the thin side depending on ambient temperature, kinda depends if your in Texas or Minnesota, but even then it should really be okay if it's decent oil. What's your oil temperature gauge saying when you've given the car a good spirted run and what's the ambient cold start temp range?

10w-40 should be fine just about everywhere but don't know how easy that is to get in the USA.

My RS2+ spec 3B seemed happiest (very consistent pressure readings & quiet engine) running on Fuchs Titan 20w-50, I'd just be sure to take it easy until the oil was up to temp, but it would get a dam good thrashing once warm.

Am running the same oil in my RS2 with no issue's, I just let it warm up before giving it any serious boost, doesn't take long say five min's in the summer, ten in the winter. That said it doesn't really get that cold over here, rarely below -5C / 20F, normally between 5C and 25C or 40F and 75F in freedom units. It would probably be a bit on the thick side for the more northern states.

Can you try another F22? As it could simply be this playing up and triggering the warning when it shouldn't as well as giving inaccurate readings under some conditions. Even if it's been replaced it could be a faulty unit.

Otherwise perhaps it could be the relief valve as mentioned above, very much doubt it's the shells if the engine is running smoothly and quietly.

I am in California so the temps never really get that cold nor would I be driving in any inclement weather anyways. Yesterday the ambient temp was around 68F/20C and the oil temp gauge never went above 90. It can get to be 100F here but once again, I probably won't be driving the car in either extreme.

10w-40 is easy to get, that is readily available. I should be able to get the 15w-50 Motul 300V here as well - https://www.motul.com/us/en/products...ition-15w50--2. Otherwise I would have to order the Fuchs https://www.opieoils.co.uk/p-68898-f...ngine-oil.aspx and pay for the shipping to the states.

I will order a couple new sensors since I have to take quite a bit of stuff off to access them. It doesn't look like the factory OEM sensors are available, I assume it's ok to run an aftermarket unit?
https://www.fcpeuro.com/products/aud...nsor-035919561
https://www.fcpeuro.com/products/eng...-crp-056919081

Let me know your thoughts

**K Simmonds** · 20 March 2022, 20:52

Item 6 in that diagram is the oil temp sensor, item number 3 is the relief valve itself.

Is 10w-40 not an option state side?

15w-40 should also be fine especially in the south, I wouldn't let the for Diesel applications put you off as long as it's got the appropriate accreditation's, though I can understand your reservations about using it in an RS2.

**K Simmonds** · 20 March 2022, 21:10

If your in California then a good quality 10w-40 should be absolutely fine all year round and under all but the most extream driving condition's as should 15w-40 for that matter but if I was you I'd go with 10w-40, especially as you mention the engine is freshly built.

90C is normal operating temp for the oil and to be honest a decent 5w-40 should be still be fine under the conditions you describe which make me think the problem is elsewhere.

As I'm a hoarder of old OE parts I really can't comment on what aftermarket senders to go for as I've never had to purchase one, perhaps some other members would be better advising you on that one...

I would offer you one however I only have a single good spare and that's for my car.

**steve briance** · 20 March 2022, 22:10

Im going to throw a grenade into the thread and run away...

There is discussion and advice here about 5w40 being a bit too thin and 10w40 or 15w40 being better to maintain pressure in an engine displaying oil light when hot.

Im not sure there is any difference between them...

The figure before the W is the oil viscosity when cold so yes, 5w is thinner than 10w which is thinner than 15w.

The second figure though is viscosity when hot and as both mentioned oils are 40 grade hot, there is no difference and as the concern only occurs hot, it is this figure that is most relevant.

10w50 would be a thicker oil once hot (or anyone remember 10w60 castrol oil??!) and should be the sort of grade to try though i can't help think that if it does make a difference it would only be masking the symptoms of whatever is causing the problem.

**K Simmonds** · 20 March 2022, 22:28

I should have perhaps gone into more depth, I was merely advising on what oil I thought would be best use given his cold start condition's (hence me asking about them) as well as trying help diagnose a problem I don't actually think is related to the oil grade currently in use.

**Mikes2** · 21 March 2022, 00:51

It's almost like the wires are on the wrong senders or you have the wrong sender. 1 bar at idle does not trigger the warning so you've either got the wrong sender in there or the wires are reversed.

RS2 - Oil Warning Light at Idle - 1.0 bar

RS2 - Oil Warning Light at Idle - 1.0 bar

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