Hi, i own an R56 Cooper S(N18),
i'd like to start by saying that i'm no mechanic so my question might sound stupid.

I recently did an oil change and even before that i noticed a brown-ish residue when opening the oil filler cap.
Is it due a cleaning or am i good to go?


Thanks in advance.

 

mileage?

Doesn't look like too much to be worried about. Maybe a bit too long between oil changes but seeing dark brown is normal. As long as you don't see any clumps of sludge hanging onto the springs and stem seals through the cap. If you do your own oil changes to see the oil you can access better.

Here is a pic of my cams dried but not cleaned yet outside my engine with 115k, dark browns normal. Your cam shaft wear looks average for something around 100k miles.

 

currently i have 125600 kilometers on mine

EDIT:
just bought the car with 124500 km and didn't see any major issues upon inspection, (also has actual service history from a mini dealer (italy), previous owner worked there)
do you think a de-coke would help with that brown-ish residue?
a well-known Mini Tuner in italy told me they've seen worse than that on both n18 and n14 engines and they would recommend the decoke which isn't that expensive (around 280 euro and a day of work)

EDIT 2:
forgot to add, i will do my own oil changes on this car every 6000-8000 kilometers max.
i changed the oil basically upon purchase despite the last oil being used for less than 6000 kilometers;
used Pakelo 5W30 XT LA (LL-04 specification) as the car has used that oil grade its whole life - some people recommended i use the 5W40 one later though.
Funny enough, Pakelo is based around 10-15 kilometers from where i live.

 

By “decoke” do you mean an intake clean? That won’t help with what you’re seeing there. It will help with dirty valves, but the N18 doesn’t seem to have the buildup problems of the earlier cars so it may not be necessary.

You’ve got a decent amount of varnish there on the cams but not excessive and probably not hurting anything. I’d just make sure to run a high quality synthetic oil and change it regularly. Don’t try engine flush or anything of that nature, as they can do more harm than good.

 

All the Decoke/ carbon cleaning you could really do is take carbon build up off the valves by walnut blasting or have your intake and exhaust manifolds ported.

if you feel like disassembling your entire head, you can clean the valves off by hand. Otherwise walnut blasting is a great option and best because you can do it with engine still in the car. Is probably what your mini tuner quoted you for. Sounds like an average shop price for this kind of job. The cleaning itself takes less than an hour to complete with 2 rounds of walnut blasting on each valve. Just the process of taking the air box and intake off to get to them is what they’re charging you for. Plus use of their tools. Very easy to DIY.

porting your manifolds would be an extreme option in regards to money and time. Machine shop would have work on your cylinder head and at that point you should be letting them do much more.

take a look down your intake manifold to see the valves after taking off the plastic air box. You can take pictures to show to a mechanically inclined person you trust with their knowledge of minis.

it won’t help with the brown tint to your cams, would sure help your car run better but not solve all possible problems.






I cleaned the valves myself and had a machine shop clean my manifolds within the head. I did not get them ported, if I did they would look much smoother for better air travel but still better than nothing . Still, this is really what a “decoke” looks like with direct injection. If you do walnut blast, you should absolutely get an oil catch can. This helps prevent oil from getting inside the intake manifold causing carbon to build up fastest. All direct injection engines could use a decarbon. Minis n18 or not absolutely should get walnut blasted if high miles and never done before. Mine is an n18 btw with 115k miles. My carbon build up on valves wasn’t too bad. I have to assume they were done once in the past. I’ve seen plenty of VW direct injectjon gas engines need carbon cleanings badly after only 40k miles throwing check engine lights. Diesels r better with carbon cause the diesel washes the carbon off the valves. On our minis there is no gasoline to wash the valves clean. Just air and the slight bit of oil that passes through unintentionally. This is what’s called oil blow by, minis r notorious for it post r53. The new ones still have occasional blow by(by design) but they’ve worked out most of the kinks(piston ring quality). I’ve added Mahle 3 piece oil rings for my pistons and catch can to combat carbon build up. The factory piston rings only have a 1 piece oil ring. Id like to keep my valves clean for as long as possible after taking the time to clean them by hand.

 

I'd be wary of any shop recommending valve carbon cleaning when shown camshaft coloration. This is not to say that carbon cleaning is not needed/meaningful in your case but simply asking what they are basing that recommendation on. Did they look at the valves? If the previous owner worked at a MINI dealer and had the car until it reached 124K, it is not unlikely that s/he had at some point have the shop do carbon cleaning.