'02 Mini Cooper, 123K. As recommended, I’ve only used synthetic oil, and I’ve let the changes go longer than you guys recommend (10K or more) but I’ve had no problems, till now. Since last oil change (local German mechanic), the oil pressure light comes on at low RPMs. A diagnostic showed it needed a new pressure sensor unit. My guy did that, now he wants to try heavier regular oil. The dealer’s service department doesn’t agree – sez Minis just use oil and I should check it often. I think I was doing that. Any ideas?
Is level low? Was it a level issue or pressure issue? Pressure can drop due to level but also do to bearing clearance and viscosity. Your pump pick up could be blocked and starving engine. Not all synthetics are created equal but I don’t think you caused issue. You are about to enter a storm by saying you changed your oil every 10k. I’m here if you need me. 
How much oil are you using? Miles per quart?
I’ve let the changes go longer than you guys recommend (10K or more) but I’ve had no problems, till now. That’s the way it works. If you let the oil remain unchanged over the recommended time/miles, you were risking damage. Sounds like extending the recommended change interval has come back to bite you.
A diagnostic showed it needed a new pressure sensor unit. What diagnostic?
* Oil pressure light on at low RPM: Is this the pressure sensor that indicated it needs a new pressure sensor? If so, you can't relay on it to say there is low oil pressure if the sensor is bad. These things are connected. It seem you are relying of an questionable sensor. Lets make sure the sensor is bad before saying the pressure is too low.Consider oil viscosity like sandpaper. The lower weight wears the rings to 5w. Using 90w will wear the rings to 90w. Then comes into play what is the minimum acceptable pressure? Increasing viscosity increases wear. So now things are worn past the point lower viscosity can deal with, so it burns oil. A thicker oil will reduce the oil burning but will wear the parts to the new thickness.
To me it would be a balancing game between wear and engine performance. Once it starts burning a quart per 1000 miles bump up the lower viscosity, by 5. ie using 5w30 go to 10w30.
Longer intervals are likely fine however you have to check the dipstick every 3-4 fuel fillups. The oil gets consumed and your level drops and the remaining oil works harder and harder ruining it.
Oh boy, you know it. Thanks.
Actually, I changed the oil more often than recommended time/miles. A reputable diagnostic tech indicated a bad sensor; it was replaced.
Not even close. Maybe 1/2 qt. per 5K if that.
Will do. Thanks.
If you want to use longer change intervals, make sure the oil has enough additives to last that long. Most oils are formulated to be changed more often. When the additives are used up, the oil can become acidic, and that will damage the engine.
Let it go then, my advice. Dewey Cheatem and Howe require me to ignore my advice and listen to other opinions, etc
Have you ever had an oil analysis done? Synthetic oil is better than dino, but not infallible. If you plan on doing 10K oil changes, I’d have a sample analyzed to make sure the oil is still doing its job after that mileage. Otherwise you are risking engine wear and sludging.
Dude don’t fight that battle. I posted about my Accord oil consumption stating that I did 10k changes on mobil 1 and I have had to argue the point ever since. I keep hearing 3k miles! It’s crazy.
“I’ve only used synthetic oil, and I’ve let the changes go longer than you guys recommend (10K or more) but I’ve had no problems, till now”
Right…How often does your owners manual require an oil change?? That’s the only thing that really matters…I seriously doubt it’s over 10K miles or more…You have been using German Castrol haven’t you?? Did replacing the pressure sensor cure the problem?? Apparently not or you would not be posting your lament…Right?
Your mechanic IMHO is not very professional, because he failed to put a actual oil pressure gauge on to determine what in fact the oil pressure was to determine if the oil pressure sending unit failed. So being being the parts changer that he is, replacing the sending unit failed to fix the problem, so now he is telling you to put in a thicker oil.
How about finding a real mechanic that is willing to perform some basic diagnostics such as using a oil pressure gauge, and possibly dropping the oil pan to check for sludge to see if the oil pump pick up screen is clogged.
Your engine ingest dirt, the removal of the dirt is a function of the oil filter. once the oil filter clogs up with dirt the oil, and DIRT bypasses the filter. Nowhere have I ever herd synthetic oil can suspend more dirt then dyno oil. And that can determine when to change the oil. Perhaps the oil maybe still good if you drained the synthetic oil after five thousand miles replaced the oil filter then put the oil back in.
IMHO. I would not let oil go any longer then five thousand miles regardless if its synthetic.
That is a valid decision. For you.
However, on my 2002 Sienna, and much highway driving south of the Snow Belt, I let my Mobil-1 EP go 8800 miles last year and had it tested by Blackstone. All parameters, including remaining additives; contamination; dirt; you name it, and it was still good, clearly would have been good at least until 10,000 miles. That is, of course, only true for my driving patterns, and those with different driving patterns will need to do something different. Ditto for a different car that may not be as solid on internals.
As I have said, you guys who specify those short change cycles for the most part are simply guessing.
I don’t think it’s wrong to guess with your own car. It’s your car and your money. It it makes you feel more secure to change every 3,000 miles, why not? If you change good oil, it’s your money and no one else’s business. If you mess up your motor, you pay and need apologize to no one. But, when you push it on others as quasi-scientific fact, guessing really sucks.
My next experiment is going to be putting in dino oil, Quaker State, and run it 5,000 miles, then have it tested. I simply do not trust dino oil in a Toyota for 8800 miles, I can get a good idea at 5,000 miles, and project it out. Some here have guessed that synthetic is really no better than dino, a few have said those who pay for it are just gullible fools, but they have no data, just guesses. I want to know, and the only way is to try it myself.
I have promised to report any results, since I really do not know yet how good dino oil is in comparison to synthetic. Too much guessing here over the years to know. This is going to take a while, because I don’t drive much here in my village so my last Mobil-1 EP is still rather new.
So can you, or anyone else remember a post with oil related engine problems where someone changed there oil every 5000 miles checked the oil weekly and never let it get low? Proof is in the pudding.
There is one thing that is far more important than simply changing the oil, and that is maintaining the oil level. Any engine will use oil, but some use more than others, and consumption can change over time. Your description of the problem sounds like you may have neglected to monitor the oil level and allowed your engine to get dangerously low on oil. I am of the opinion this is one of the major pitfalls of extended oil change intervals: operators who never open the hood and check the oil level. If you are going to use an extended oil change interval, you need to open the hood and check the oil level from time to time. Learn what your car’s rate of consumption is, and check the oil before it will be due for another quart.
One other thing: your car is designed to use one of only a few kinds of oil. Only certain brands meet the specifications for your car. Only use synthetic oil in the weight approved for use in BMW/Mini engines. DO NOT try to cover up the problem by using an oil type or weight not approved for your engine! If you still have low oil pressure issues, and it has been verified by a mechanical oil pressure gauge, your engine is shot (excessive bearing/journal clearance).
1/2 qt. per 5k miles is NOT an oil consumption problem ! !