I just picked up an 02 Mini Cooper S with 95k on it. There was only one previous owner but a private dealer sold it to me. He told me the orignal owner used synthetic oil but he put regular oil in. Why he would do this, I don't know. He drove the car for about 5,000 miles, so I'm assuming he did 1-2 oil changes with regular oil.

Is it safe to go back to synthetic, or is it too late?

He also used regular fuel even though the original owner pumped premium. Hopefully the last 5k miles werent too bad for the car.

 

Dont change back, the engine could explode! LOL

Just put the synthetic in it, it will be fine.

 

Definitely go back to the synthetic oil. Biggest reason is it is what the manufacturer calls for. Other reasons are that it is simply better and affords better protection for your MINI's engine.

You'll be fine going back to it (synthetic oil). I recommend AmsOil, but there are others out there that perform well; everyone seems to have their favorites. I would change the oil evert 7000-7500 miles.

 

MINI recommends Castrol Syntec. It doesn't hurt if you go from synthetic to regular or regular to synthetic or any combination back and forth between the two. All motor oils meet the minimum oil standards, but synthetic does not break down like a conventional motor oil does. It also has better cleaning properties and resistance to heat. Just change back to the recommended synthetic oil and you will be fine. The interval in my 05 MCS is a little over 15,000 miles. With synthetic this is more than possible.

As far as your fuel is concerned, the only differance between regular unleaded and premium is the octane rating. Lower octane fuel in a Cooper will result in pre-detonation or "ping". This shouldn't "hurt" the engine, but it will have an affect on the fuel economy and available power since it isn't combusting properly. No big deal though, just fill up with the recommended premium at your next fill up and take it a little easy with the tank of low octane to prevent pinging.

 

I'm also in the change back to synthetic oil & enjoy camp. IMO no harm has been done.

I'm going to have to disagree with you Mr Death. If you can hear an audible ping from your engine, "you are hurting your engine".

 

Thanks guys! Ends up the guy DID use synthetic oil, so it has been treated to synthetic oil its whole life. I'm happy about that

I was under the impression that you can damage seals by using regular oil after you've been using synthetic. You'd think I'd know better after 8 years of working on cars and doing just about everything imaginable to them

 

Odds are you won't hear the MINI 'pinging', it has a knock sensor and dials back the timing to stop it. It's not instantaneous, though, and the knocking it senses before it retards timing can and will harm your engine if it happens often enough.

 

When you detonate your fuel mixture early, the compression is lost through the intake valves that have not closed yet. You definately lose power, but I'm not so sure you are going to damage anything over a short time. It's true, your engine computer will do it's best to "fix" the problem, but obviously can't eliminate it completely. With super charged or turbo charged engines the risk is greater, but over time any engine will start to melt pistons if pre-ignition goes on for a decent length of time. This is why I cautioned the OP about driving hard on low octane fuel.

 

Actually, if I may disagree with you, detonation is when the fuel burns so quickly after normal ignition that maximum pressure from combustion is reached before the piston reaches top dead center. The combination of the faster than normal burn rate of the fuel and the still-rising piston results in a higher and faster pressure spike that causes the ping. This is where the fuel's octane rating comes in; the higher the octane is, the higher the compression pressure can be, before the fuel starts burning too fast (i.e. exploding).

Pre-ignition is when something that's very hot inside the combustion chamber (usually a bit of carbon) causes combustion to start before the spark plug fires. If this happens after the intake valve closes, this causes peak internal pressures to be even higher than with detonation and can damage an engine in a short time. When pre-ignition gets really bad, it can cause a backfire, which is when burning gases vent past the intake valve. This used to cause big fireballs to come out of carburetors, when all the fuel that was in the intake pipes ignited and would shoot out the carburetor's throat.

If you want, I'll track down a source for the Pratt and Whitney aircraft engine textbooks that I found do a good job in explaining this.

 

that little thing that says use Castrol only is just some marketing thing put up by castrol and BMW probably got a big cheque off that. there are better oil out there than Castrol but for day to day driving. any oil that meets the requirement is fine.i know a motul rep that daily drive+ lightly track his Civic SI and he did an oil analysis and found that their oil was still giving protection after 15000 miles of mix driving. so i run motul on my mini which is a daily driven weekend racer.(plus, i get motul product at cost)

as for pinging. it will hurt your engine . i dont know how to say it better than wikipedia so i just cut and paste it

"Pre-ignition (or preignition) in a spark-ignition engine is often confused with engine knocking. In fact, it is a different phenomenon, when the air/fuel mixture in the cylinder ignites before the spark plug fires. It is initiated by an ignition source other than the spark, such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events. Dieseling or run-on is the same phenomenon, but refers to the engine continuing to run after the ignition is shut off with a hot spot as an ignition source for the fuel air mixture. Because both preignition and engine knock sharply increase combustion chamber temperatures, either effect can increase the likelihood of the other effect occurring. Given proper combustion chamber design, preignition can generally be eliminated by proper spark plug selection, proper fuel mixture adjustment, and periodic cleaning of the combustion chambers."

bty. my 05' MCS pings,it has 40K mile, no engine light. i put nothing less than 92 in it, 94 for race days. so the computer obviously is not doing a good job on controling what's going on inside the engine. it's up to you to protect your engine.

 

I'd suggest running some Techron through your car. I've had good luck using it in the past & I pour a bottle in the MINI at every oil change.

 

If there is no audible pinging, (and it's very unlikely that there will be), your engine should be fine. The trade off for lower octane gas could be slighty lower performance and maybe a bit worse gas mileage. Economically speaking, any reduction in gas mileage is likely to be more than offset by the lower cost of regular gas.

One of biggest waste of money in the nation is people using premium in cars that don't need it, which, except for some older cars with no computerized engine adjustments, are most of them.

Many new cars, Mustang for one, come with two hp ratings, one for regular gas, and a slightly higher one for premium. It's your choice, but your engine isn't going to self-destruct because you are feeding it regular gas.

Gas grades of "regular" mid-grade" and "premium" are not the same as good, better and best. The oil companies would like to believe that is the case though because their already healthy profit goes though the roof on the higher octane grades of gas which cost them about 2 cents extra per gallon to make and they often charge as much as 15 cents/gal. per grade extra at the pump.

 

Lower octane definitely lowers mileage in the Mini. I've been putting 91 octane in ours, while my wife always puts in 87, so the car tends to alternate between the two. Now, after about two dozen fill-ups, I've noticed through both the computer and my own manual calculating we lose about 2 or 3 mpg while running the lower grade fuel. Still testing this, though, so I won't claim this as definitive.

 

It's great having a modern car with a knock sensor. No more grabbing the timing light & retarding the timing when you got a load of bad gas from the mom & pop station.

PS... Don't fill up at the mom & pop stations. You never know what you'll end up with.

 

Geez... my car was $27,300 dollars with tax and all.

who the hell cares for 30 cents more for the best gasoline that fits the specs for the car?

never understood this. Eat 2 less donuts a week, buy shredded wheat instead of raisin bran... mini = deserves some love

Hi crashton!! good to see you around!! I havent posted in a long time

 

Give up donuts! Not sure I can do that, but I do agree it doesn't cost too much more to run the proper fuel in our cars.

Hello El_Jefe, where have you been?

 

The 30 cents a gallon savings isn't really the point. It's the mistaken idea that somehow your MINI will self-destuct or be damaged beyond repair, (or at all), by using regular gas. That is, IMO, a myth that needs to be dispelled just because there is no truth in it. No one is saying you can't use the most expensive gas you can find if it makes you feel good.

 

If the engineers who designed my car say it is supposed to use premium who am I to second guess them? Just because someone on the internet says it's ok to run regular doesn't make it so. We all make our own choices. I have no problem paying an additional 2 bucks per fill up. Yep I feel feel fine doing it too.

I'm not sure anyone is saying you will kill your motor by using regular. If that makes you feel good then heck it's your car. If you do hear an audible pinging, then yes you are hurting your motor.

There is a knock sensor & if I had no other choice & had to use regular I would put a gallon or two in to get me to the next station for a fill up with high test.

 

I use premium.

 

a friend of mine works for kumho tires canada and they use minis and other german cars to do tire demos with.those cars were driven on tracks with regular gas . and guess what. no ping. cheap gas wont hurt your engine in a short term period on daily driving. but if you run your car hard, im sure there'd be some difference in engine wear between regular and premium over time(that's if the car is noticably pinging at high load). i use premium because i think it's a cheap insurance for a longer lasting engine

 

I got a little carried away in some of my responses. I had occasionally noticed people posting things like. "I accidentially put regular gas in my MINI, is it damaged?" and other such things, sometimes sounding really upset and afraid they had done something terrible to their MINI.

The occasional use, or even regular use of regular gas is simply not going to damage your MINI. It will take care of itself. That is why premium is "recommended" and not required.

I use premium and sometimes mid-grade......depending on the brand of gas I sometimes get less of the minor "cold start" stumble from mid-grade than from premium...not sure why unless it's from the type of octane booster they use.

Of course I am "just a guy of the internet" and if it makes someone feel more secure to always use premium gas then by all means that is what they should do.

I just hope they don't panic if some regular gas somehow sneaks into their baby.

 

I don't think you got carried away. Lots of folks freak & think they've hurt their baby by putting in too low of a grade. I think what we are trying to do here is calm their fears.

I agree 100%. My car starts harder with regular so I use what it seems to like. As long as there is no audible pinging you are fine running regular.

From one "internet guy to another". Happy motoring.

 

One word: Cheapskate. hope he didnt mess up the engine with his cheapskated-ness

 

I stated my case on the oil, now for the gas issue:

I would read the threads that already exist on NAM on this topic, and there are a few. Personally, I would do what the manual states; use the recommended premium fuel.

Regular gas (Below 91 octane) will be OK in an emergency or for a short period of time, but keep in mind the ECU accounts for the lower quality fuel and retards the timing accordingly; you lose performance and fuel economy for a $3.00 savings per tank-hardly worth it.

ultimately it is your MINI; do what you believe is best for it. For me I would rather spend the extra $3.00 a tank and have the piece of mind.

 

"cheapskated-ness"? I think I like it. W00t! New word for the vocabulary.
Thanks, dude.