New 2010 Cooper S manual. I drive 128 miles round trip each day on the NJ Turnpike... Had my mileage up to 41-42 each day.

This past weekend at 3900 miles, I changed the oil and filter – putting in 4 quarts of Mobile 1 Extended 5w20 and ½ quart of Marvel Mystery Oil. The last two days my mileage has gone down to 36-37 with no change in driving style .

I checked the (difficult to read) dipstick last night, and it seems full, but it is kind of hard to tell. The only reason I can figure other than oil problems is that it has been cooler over the last two days – maybe the tire pressure is lower and impacting mileage? I will check that tonight when I get home.

My dark fear is that but I messed up tightening the filter and oil leaked! I used an extractor so there isn’t any leakage from the bottom drain plug!

I figured I would ask you more experienced (and probably wiser) Mini Folks about your thoughts on my oil change and mileage decrease – it is a mystery to me!

 

I am not sure about using 5w20 oil, such a lightweight oil, on a Mini. It is not a viscosity recommeded Mini.

 

Thanks - I'll take the insight. I was unsure, and thought 5w30 would be better, but the store was out of Extended so I went with the 5w20.

 

Tire pressure is the first thing to check.

I question the use of MMO in the oil and the viscosity and type of oil. MMO is a thinner (contains solvent), a small amount in the fuel tank to add lubrication to the fuel is OK, but thinning an already thin oil like 5w20 Extended Performance, lowers the viscosity. I recommend draining the oil and using Mobil 1 0W-40. It has been tested and approved for use in the R56.

Adding anything to the oil on top of the original engineered formulation risks reducing the protective and flow properties of the oil. Some additives are not compatible and the proportions of additives in an oil formulation are critical. MMO was designed for carbureted vehicles back in 1917 to be used in the fuel tank.

 

If you intend to change it fairly often, you don't need the exteneded interval oil anyway, just buy the "regular" 5W30 Mobil 1 or buy the oil straight from MINI - it's about the same cost. I would recommend using the factory filter too - that way you can't have a warranty claim problem down the road. I can't understand how folks can spend $30K for a new car then cheap out on the oil and filter.....

I do agree with changing early as you did - I changed mine right before a trip at about 3K and it was nasty, since then it's been pretty clean every time I've changed it - I'm now going at 7,500 mile intervals, which works out to twice a year.

However, I (and MINI agrees) do not find the need to add additional additives like the Marvel Mystery oil.

Be careful tightening the oil filter cartridge, it's made of plastic - the seal is made by the o-ring, not by how tight it is. Lube the o-ring well before you reinstall the cartridge - you only need it tight enough so that it doesn't loosen up again.

At your next change interval, try going back to regular MINI oil and filter and see if it changes. You're right tho, weather conditions as well as driving conditions can easily affect your mileage by 1 to 2 mpg.

That's why all the adds say YMMV!

 

Wrong oil. Don't risk your warranty!

MINI recommends their oil. If that is not available then these are the approved oils.

The oils listed below meet MINI's Long-life rating and are acceptable for use in MINIs in the US market with gasoline engines.
Long-life rating LL-01 Approved Synthetic Oils for the US Market
- Castrol Syntec European Formula SAE 0W-30
- Mobil 1 SAE 0W-40
- Pennzoil Platinum European Formula Ultra SAE 5W-30
- Valvoline SynPower SAE 5W-30

 

I would leave the oil filter in place and dump that 20W oil and Marvel crap NOW - and go with Mobil 1 0W/40........ You will be happy with the MPG's coming back - I guarantee it... Hand calc your MPG, don't let the car tell you what it thinks it is.... Check the oil level when cold - much easier to read....

We do run Mobil 1 advanced fuel savings 0W/20 in a 2005 Mazda 3, but only because that's the recommended oil weight.

http://www.mobiloil.com/usa-english/...l_1_0w-40.aspx

 

LL-01 oils are if you are going to keep up with the computers recommended oil change schedule. If not a regular oil will be fine for less than 5,000 mile oil changes.

My car is currently showing 13,000 miles till its first computed oil change. This is with nearly 6,000 on the odometer. Going 19,000 miles on the first change since new sounds crazy to me. That is why I change with less than 2k on the odometer. Will probably go again here in a few weekends when I have some time to do it again.

Oh and I went with Mobil1 0w-20. It is actually getting better mileage than my wife's JCW with the dealer Castrol 0w-30. If you have to change always go thinner not thicker than recommended. Full hot viscosity is not much difference. However start up cold viscosity is much better and protecting with a thinner oil.

 

Many thanks to you wise Mini folks - what I have learned (and my plan of action):

1) Make sure tires are inflated to exact recommended level
2) Pull out the 5W20 and replace it with Mobil 1 0w40
3) No more Marvel Mystery Oil in the crankcase!

Thanks again to all.

 

Just a clarification:
Mobil one 0w20 is not a recommended oil.

Mobil one 0w40 and Castrol 0w30 are.

I would not put a 20 weight oil into a Mini especially if your car has a turbo or supercharger.

 

I don't think there's an issue with the 5W-20 oil you have in there, and I wouldn't go out of your way to remove it. Just wait for your next change and use a recommended oil then. But in the mean time, your engine isn't going to fall off or anything.

In fact, the slightly lower weight oil will be better for your cold startups because the viscosity is a bit lower (nearer to what it should be at temperature).

 

Thanks again - I did check the inflation this morning and the data came up:

RF: 36
LF: 38 - perfect
RR: 35
LR: 37

I am going to adjust the air at lunch - and we'll see how it goes.

 

Just wanted to clarify some things that confused me in your comments:

5w20 - 5 is the cold winter viscosity, and 20 is the hot viscosity which is quite thin.

When compared to 5w30, there should be little difference in cold startup but the difference is with the protection of the engine when it is hot (and perhaps mileage). Of course there can be differences across brands.

 

With a new car and the proper oil you do not need to sludge up your engine using additives.

If you want to use an additive you should put some "Techron" in the gas tank every 5,000 or so miles to keep your fuel system clean.

Modern oil does not need additives unless there is a problem with the engine you want to cover up. They sure don't repair anything permanently.

 

Isn't the CastrolSyntec 5W30 ok to use too?

 

My feeling is that if it is the right viscosity and it is synthetic, i am fine with it in my street car. I think a proper oil change interval is also a must.

Some must have exactly the oil Mini recommends. I can respect that opinion as well. If i put a car into prolonged high stress such as the track, then I tend to go with 'real' synthetics such as Castrol 0w30 or Mobil 0w40. While the wear protection of these are average, their high heat stability is better.

 

Hello friends - just wanted to give an update. After your good advice I did the following:

1) Inflated the runflats to exactly 38
2) Pulled out the 5w20 and replaced it with M1 0w40
3) Drove to work and got 42.3 this morning.

Thanks to all again!

 

MPG's are back as predicted - Sweet.......

 

To clear up your confusion…

First, you're making a common mistake that 'w' means 'winter'. It doesn't. It doesn't stand for anything, it just indicates a different set of SAE test parameters. It does give some indication of "cold" (as in, 100 ºF instead of 212 ºF) start-up viscosity, but just because both 5w-20 and 5w-30 start with '5' doesn't mean that their start-up viscosities are the same — they're not. In fact, the start-up viscosity difference between a 5w-20 and 5w-30 is greater than their operating (212 ºF) viscosity difference!

Looking at the datasheet for Mobile 1 Extended Performance motor oil…
the 5w-20 flavor has an expected start-up viscosity of 47.4 cSt, while the 5w-30 is listed at 61 cSt — a difference of 13.6 cSt (despite both being listed as "5w" oils)
moving to operating temperature expected viscosities, the 5w-20 is listed at 8.9 cSt, and the 5w-30 is listed at 11 cSt — a difference of only 2.1 cSt.
And, no it's not the percentage that matters; viscosity doesn't work like that.

But the OP put in Mobile 1 0w-40 instead of the 5w-20…
start-up temp viscosity: 78.3 cSt (was 47.4 cSt — much closer to the operating temp ideal viscosity)
operating temp viscosity: 14 cSt (was 8.9 cSt — only a 5.1 cSt difference at operating temp… again, even less when corrected to 220 ºF for the N14 engine)

So (just looking at viscosity, mind you), the 5w-20 oil is much less viscous at start-up (better for your engine at start-up) than the 0w-40 (and the 5w-30) while only slightly less viscous at operating temperature — the exact opposite of what you were saying was the case.

And while you're scratching your head over that one, I'd highly recommend this excellent discussion of motor oils over on the ferrarichat.com forums.

Note: I'm not arguing against following the recommendations from MINI… just saying that the 0w-20 the OP had in there wasn't "wrong enough" (and in fact was better in some measures) to warrant going out of your way to extract and replace (which he already did by now anyway). But this Marvel Mystery Oil stuff the OP had in there as well… I'm a little wary of that.

 

All oil brands and grades can be quite different. Their viscocities are different. You cannot say 0w20 is universally heavier at startup than 3W30 for all brands either. The rule of thumb generally holds, 0w20 is generally lighter than 5w20 at start-up.

I hope I cleared up your confusion.

 

You claimed that the start-up viscosity of 5w-20 and 5w-30 was roughly equivalent, while the operational viscosity had greater difference (your assumption being that 5w = 5w and 20 != 30). I showed this was not the case, using the specific 5w-20 oil that the OP selected, and the 5w-30 oil of the same product line. Then I also included the specific 0w-40 oil that the OP replaced the 5w-20 with, just to show how it compared to the 5w-20 and 5w-30 I had just discussed.

Nobody said anything about 0w-20, 3w-30, etc. So, the only confusion I have is in regards to what, exactly, you believe you're clearing up.

Perhaps you felt slighted at having been corrected, and felt the need to re-assert yourself?
It wasn't my intention to rub anyone the wrong way; just to clear up a fallacy being circulated.

EDIT:
While we're on the subject, though... depending on the viscosity ranges required for each SAE rating on multigrade oil, you may be able to say that grade X is universally heavier/lighter at start-up than grade Y (across product lines and across manufacturers). These numbers aren't dreamed up by oil company marketing departments, they are assigned by an independent agency based on laboratory testing and hard data.

 

My mini seems to like penn ultra 5w30 and lubromoly mos2 antifriction additive alot.A little Moly is the only additive i will put in my mini, no mmo for mine.

 

Yes. finally some good sense... from no sense

What is 3W30??

 

No idea.
You're the one who brought it up.

 

Wrong. It is in your post. Please read your ??? info.