Oil top up

[prtyqwerty]

Hi,
I recently picked up an MRC mapped C6 RS6. Check oil light came on the other day but then went off once I pulled in and hasn't come on since, possibly a faulty oil level sensor? The issue is the last service it had the oil used was VW / Audi Longlife 5W30 540 00 / 507 00.

I went to my local Audi dealer and they said that 5W30 had been discontinued they only stock 0W30 and it "should be fine" to top up using this oil and that next time I do an oil change I should use the 0W30.

"Should be fine" isn't really a phrase I am comfortable using when it comes to 700 odd horsepower engines.

What should I do at this stage - top up using a similar spec but different brand 5w30?

Or do an oil change to a different brand entirely and get a new oil level sensor while I am at it?

[IanH755]

As it's mapped (and therefore not Audi OEM spec anymore) I'd just get the best 5w30 (or 5W40 as an option too) Ester based Fully Synthetic oil you can, rather than looking for the OEM oil, and do a full oil change just because you've only recently bought the car and it'd give you peace of mind that the oil is up to the task at least. Also remember that, as a dry sump engines, you have to check the level when the engine is hot, so immediately after a drive rather than letting it cool first like you would with a more traditional wet sump car.

I personally use Fuchs Titan Race Pro-S 5w-40 (when mapped at both 740hp and 930hp) which I bought from OpieOils but there's quite a lot of high-end oils which will all perform at a similar level.

As to the oil sensor, they can be a bit "glitchy" at times. Unless it's bringing up a fault every few days (when the oil is full) I'd not bother with a sensor yet however I'd keep track of how much you're using. Some cars use a lot of oil and it's usually dumped into the Intercoolers due to one or more dodgy "non-return valves" in the PCV system - IIRC someone had over 1Ltr in just one IC - so it's worth tracking just to check on the PCV health that way.

[Jim Haseltine]

I measured 750ml in the right IC and 250ml in the left, collected in less than 2 weeks from a previous draining - after that I mostly gave up measuring it. Think my last check was a total of 500ml from the pair of hoses.
The main culprits were parts 19 & 22 on this diagram - they're hoses with non-return valves. They're mentioned very briefly towards the end of one of the Audi RS6 training videos with a comment something about blue smoke on starting.
https://nemigaparts.com/cat_spares/etka ... 41/103500/
Prior to replacing those parts I'd also replaced 2 of the 3 non-return valves in the main PCV pipes (parts 1 in the diagram), the PCV separator itself (part 25) because it had a split diaphram and part 6 (which has two non-return valves) because the mounting flange broke whilst I was doing another job. None of these latter parts made much (if any) difference to the amount of oil in the pipes and didn't stop the car smoking every 2-3 days, it was parts 19 &22 that did the job.
Do not trust that a new valve will work properly - luckily I tested mine before fitting, one was supplied faulty.

[prtyqwerty]

Thanks, guys, and yes I agree with you @IanH755 - a complete oil change and a new sensor locally first thing in the new year. Once COVID settles down in the spring I'll make the trip to MRC for a full service on the engine and gearbox.

The car had been sitting for 6 months bar only being used a handful of times in November to do a test drive and pre-purchase inspection so in all likelihood just a random error.

Have heard about the oil in the intercoolers, complex engines with complex problems!

[welwynnick]

Other things being equal, a 0W30 oil is better than a 5W30 oil, so the expression "should be fine" is nothing to worry about.

I agree with Ian. A highly stressed engine, and especially an older one at that, may benefit from using 5W40 oil instead. That's what I do.

Getting the latest and greatest modern oil with all the specs, standards and certifications under it's belt isn't necessarily a guarantee of finding the best oil. These days a lot of the development in oil goes towards reducing friction, reducing emissions and extending service intervals, which are highly unlikely to be priorities for readers in these pages.

Correct me if I'm wrong, but IIRC Audi recommended a VW 502 00 oil when the the RS6 was launched, and that's still a good baseline.

Nick