E46 M3 v E92 M3

[rassi]

I would say E92 with the caveat that a higher mileage one would benefit from replacing rod bearings. Throttle actuators the only other weak point but otherwise a very solid engine and the E92 doesn’t rust like the E46 or have the problem of cracking rear subframe.

[Gruber]

rassi said:

I would say E92 with the caveat that a higher mileage one would benefit from replacing rod bearings. Throttle actuators the only other weak point but otherwise a very solid engine and the E92 doesn’t rust like the E46 or have the problem of cracking rear subframe.

It’s a tough one - £15k should get you a very good e46 - but I’m inclined to agree with Rassi and go e92. But ask me tomorrow and I might have changed my mind. It feels like a bigger car, but it also feels much more modern inside and I just love that V8. My personal pick would be DCT over manual, but each to their own.

But then... can you find a manual e46 M3 CS with reasonable miles within budget? If so, get that.

Oooooh it’s difficult, isn’t it?!

[Front bottom]

Owned both. Loved my manual E46 and kept it for a record (for me) 5.5 years.

Now own an E92 DCT and I'm always finding excuses to get out in it and enjoy that V8 and the more accomplished chassis (imo).

[Junior Bianno]

I've had an E92 DCT and loved it - really is a fantastic car. Watch out for those throttle actuators though - got mine replaced under AUC warranty but would have been a big bill otherwise.

I'm on the lookout for an E46 at the moment though - ideally a manual CS. I'm seriously lusting after this but due to travel not going to be ready to go for 2-3 months.

https://www.pistonheads.com/classifieds/used-cars/...

Silver-grey, big brakes, all the right inspections and sub floor work. Will be a cracking buy for someone

[SebringMan]

rassi said:

I would say E92 with the caveat that a higher mileage one would benefit from replacing rod bearings. Throttle actuators the only other weak point but otherwise a very solid engine and the E92 doesn’t rust like the E46 or have the problem of cracking rear subframe.

A good call. The Rod bearings seem to be an issue at any mileage it seems. Some have let go at 21k like on M3Cutters and others are still on theirs above 100k. When I asked Autobahn they said they saw a similar number of E90s in for rod bearings when compared to E46s; I'm debating getting mine done on my E46 M3; it will see a couple of track days.

The running costs are similar for the two on paper. Different in each of the sectors but similar. MattOz should be able to comment after owning both and getting both serviced from the same dealer/garage.

[Welshbeef]

Why do the main bearings go on these cars? Oil starvation of some kind or a slight pickup from the conrod?

[RS250_Steve]

Welshbeef said:

Why do the main bearings go on these cars? Oil starvation of some kind or a slight pickup from the conrod?

I've never seen any concrete evidence. I suspect a combination of tight clearances, cold starts, high revs and narrow journals.
There is a belief that a lot of the damage is done early in the engines life... who knows.

[Front bottom]

RS250_Steve said:

Welshbeef said:

Why do the main bearings go on these cars? Oil starvation of some kind or a slight pickup from the conrod?

I've never seen any concrete evidence. I suspect a combination of tight clearances, cold starts, high revs and narrow journals.
There is a belief that a lot of the damage is done early in the engines life... who knows.

There are suggestions of using a slightly thinner oil to help protect more on cold start, which some owners swear by. I'm not sure I'd go against the BMW recommendation though...

[SebringMan]

Welshbeef said:

Why do the main bearings go on these cars? Oil starvation of some kind or a slight pickup from the conrod?

There is no conclusive proof either way, and the rate they go at is very random.

When I spoke to CPC and Autobahn (these guys are doing mine as a preventative measure) they were saying the rate they go at is random. They had removed some from cars that were trashed at 75k, and others which were fine at 140k; there is literally no evidence to support either way.

One thing that is interesting is how BMW say to not top the M3 up to the maximum oil level line if you can help it. That would insinuate that not only does it hurt power with that close a tolerance but it will also aerate the oil; if the level is excessive in the crankcase the crank will literally 'smash' the oil and bring about air, which of course can impede oil pressure.

It would be interesting to see if the dry sumped S54s suffer from this issue.

As for oil levels being excessive here is an interesting video; if it will play. I was told that it made a diferenece years ago, but I underestimated just how critical it was.

https://www.motortrendondemand.com/detail/how-oil-...

Front bottom said:

There are suggestions of using a slightly thinner oil to help protect more on cold start, which some owners swear by. I'm not sure I'd go against the BMW recommendation though...

The one thing is a higher oil viscosity does have a higher shear resistance. That is probably handy in an S54 which has high piston travel speeds due to its RPM and stroke which will exaggerate the airing problem.

If the oil was that big a problem I suspect we would have seen many more failures by now too.

[Patrick Bateman]

People who swear things like a thinner oil being better are rarely basing it on actual evidence.