Low Oil Pressure at Idle Info

[TostitoBandito]

I've used a BMW/Ferrari approved full synthetic Euro 5W40 for the last several years. Less noise and less burn-off than the OEM 5W30 oil. If you're in a cold climate and drive your car in the winter though, be careful about increasing the cold viscosity. The owner's manual has some temperature guidelines if I recall.

[Nate047]

My 99M3 owners manual says the oil light may flicker at idle when the motor is hot.

Really? I'm not doubting but could you take a picture of where it says this?

[Nate047]

Bump, would like to see the page in the owner's manual as referenced above, if possible.

[MauiM3Mania]

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[shogun]

In case you do not have one, download here , Owner's Manual | Part No. # 01 41 9 790 377 | 3.5MB https://www.bmwsections.com/docs/3series/

[Nate047]

Good looking out guys, thanks!

[Tehvic]

So I did something stupid... the PO of my car was running a 10w-60 racing oil in my car. I went in to my local dealership and had a conversation with them about this and ultimately was talked into dropping down to a 5w-30. Big mistake. Today, the light has been over active in the idle position and I've developed a very pronounced lifter tick... Needless to say, another full oil change is in my near future to take it back up to 10w-60. I'm almost convinced that it's not so much a mechanical break down of the car (oil squirter issues), rather, with aging internals and larger bearing clearances etc...

Either way, I'm starting to consider a rebuild...

[MIKYZZ4]

Tehvic,can you provide further info?,
Like engine specs and engine mileage, time/mileage interval between previous oil change?

[MauiM3Mania]

I went in to my local dealership and had a conversation with them about this and ultimately was talked into dropping down to a 5w-30. Big mistake. Today, the light has been over active in the idle position and I've developed a very pronounced lifter tick... Needless to say, another full oil change is in my near future to take it back up to 10w-60.

Dealerships stock 5w-30, so that's what they push.

There is a middle ground... 10w-60 is not the correct weight for an S52. 5w-30 is quite light in my opinion, particularly for summer usage. Try a quality 10w-40.

I know some people like a 10w-50 and obviously 10w-60 but both are band-aids for other issues.

[MIKYZZ4]

xxW-40 for summer & xxW-30 for winter,
A tried and true formula for my first car,
and seems to still apply today, with the addition of a full synthetic formula!
At least that's my educated and researched opinion, yours may vary.
Higher levels are due to special circumstances and requirements, as stated in above post.

[NeilM]

I haven't been able to find a BMW spec for idle speed, but anecdotally 500 rpm seems low. Idle speed is not adjustable as such, since it's controlled by the ECU via the idle control valve. Some aftermarket engine tunes will bump the idle a bit. The ICV is located under the intake manifold, and is certainly known to malfunction, or to leak vacuum at its rubber gasket mounting. A small vacuum leak anywhere else in the intake tract (also common) may also affect idle.

10W-60 is an unusually heavy weight oil to use in this engine, and wasn't even readily available when the car was current. AFAIK BMW started using it with the E46 M3's S54, which had rod bearing issues in the early versions. Oils commonly used for the S50/52 are 15W-50 for track/high ambient and 0W-40, 5W-40 or 10W-40 otherwise. I wonder whether the PO's use of 10W-60 was an attempt to address oil pressure issues?

It's definitely worth checking for the dreaded cracked oil pump pickup tube, but man, it's a royal pain to do.

Without an actual oil pressure gauge it's not really possible to draw conclusions about the state of an engine's lubrication system. You can buy shop oil pressure test sets for smallish money (Harbor Freight, etc.), or fit aftermarket dashboard gauges at rather higher cost.

Neil

(Note: Originally posed over in the other thread, copied here.)

[TostitoBandito]

Yeah if you're having oil pressure issues with 5w30 but not 10w60 then there's probably something wrong inside the engine or oil pickup/pump. The BMW 5w30 oil that the dealers use should work in these engines with no issues. I personally use a BMW-approved (longlife-01) 5w40 full synthetic, but there are many oils out there that people use for performance or climate reasons.

[Tehvic]

So I re-changed my oil yesterday back to the POs recommended 10w60 BWM fil synthetic... car runs a lot better than it did. Light still flickers. Crazy thing is though, with the 5w30 I had in there, I'd have to rev over 1k to get it to shut off. Now, goes off at about 650-700ish. I know it's a harsher oil to use for my bearings, but I just felt the 5w30. I didn't like the way the engine performed. I think toward winter I'll definitely drop it down a bit, but for these super hot days I'm reluctant.

My car is a 1997 M3/4/5 with an unmolested 113k miles on it.

Someone brought up a good point about the ICV... the PO put in a cold air system, I'm wondering if there was damage done to the ICV at swap? Something I'll look into.

Thanks guys for all the info!

[Nate047]

You could instal an oil pressure gauge if you're really worried about it. But you'll probably just learn to live with it, after you end up doing everything listed in this thread and it still happens. IMO rebuilding a motor for a reason like this is asinine.

[Tehvic]

I have to agree with you Nate... I won't truly worry unless the light comes on at operating speeds (cross My finders)... other than that, I'll just tease the throttle a bit at lights and watch it close

[marvinstockman]

A 10W60 weight oil in the warm weather should not be a problem for your bearings. Remember, when cold, the oil runs/performs like a 10 weight oil, and when hot it runs/performs like a 60 weight oil. The main reason manufacturers use light oils, like a 5W20, is to increase mpg.

The heavy oil maintains an oil film between rotating parts, under a very have load, a lot better than a 20 or 30 weight oil.

In your case, you've probably got increased clearances, and the heavy oil stays in place better. Remember, if you lose the oil film, the engine will seize up, as metal on metal is a no-no.

[MIKYZZ4]

I have a simple question,
Has oil pressure been measured & verified for both grades of oil in this engine>5w-30 & 10w-60?

[Tehvic]

Not under my ownership, no. Sound like that would be an expensive test as the 10w60 runs around 15/qt, haha The PO had tried to diagnose the problem with his mechanic for a while including a full bottom-end rebuild, but could never pin point it. Thats why my assumption is that it has to be the internal "oil squirters" or something that was overlooked like the pick up tube. I still think the car idles too low, around 500-550 RPM and thats what the light comes on. I need to mess around with it and see if I can get idle to around 700. I'm wondering if there was something messed up with the ICV? Not sure...

[pbonsalb]

Idle rpm is in the tune so if you screw out the stop it could affect the tune. I can't recall factory idle but might be 550. I use 850, in a tune.