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Lack of synthetic oil can do that?

The question at hand is about a co-workers car. It is a mini-cooper with over 140,000 mile son it. Not sure fot he year ofthe car, but he bought it used with 50,000 on it and that was three years ago.

He was on a trip last week to the Rockies. On his way there one of his six cam shafts sheared. When he took it to the dealer to be fixed the mechanic asked him if he used sythteic oil. He replied that used a blend and has since he owned the car.

The mechanic stated that was why the shaft sheared.

This is not a question of a warranty or anything, just of curiosity. Can using a blend really make so much of a difference as to have this happen?

6 camshafts in a mini engine? I have never heard of this engine (must be tough to get the valve timing right)and then one shearing? due to a different oil, something is out of wack here.

Not likely but possible.

However if he decided to use Mini’s 1yr/10k-12k oil change interval and improper oil spec it could ruin the engine.

I don’t think he let the changes go that far, but I don’t know. Just seemed odd to me that this would happen. Shearing of this component, to me, does not bring to mind improper oil.

The 1958 Oldsmobile suffered camshaft failures on some of its cars. The problem was traced to certain brands of multiviscosity (meaning 10W-30) motor oils. Apparently, some oils didn’t stand up to the high valve spring pressures. As I remember, Oldsmobile issued a warning that multiviscosity oils were not to be used in the engine. That was over 50 years ago and oils and engines have improved since then. I mention this to point out that in the past, camshaft failures have been traced to the problem with the motor oil.

Without seeing the parts and the way they are damaged all this discussion is acedemic.

Synthetic oils don’t break down in heat as fast as conventional oil. So, theoretically on the trip in the Rockies a lot of stress was put on the engine and it got hot. The mix of conventional oil wasn’t enough protection as the molecules in the conventional oil sheared and became ineffective at lubricating. Eventually this leads to more heat, more stress, and more molecules shearing in a vicious cycle. The friction in the area damaged got so significant that a very hot part broke in someway.

There are a lot of things we don’t know, brand of oil? Last date of oil change? How many miles between last oil change and the “event”?

Many European cars are now requiring Synthetic oils. If you go with conventional in these cars you could be taking a risk. It seems the Mini Cooper is one such car.

If this engine is turbocharged, yes, using anything other than a full synthetic oil could damage the engine (although something seems fishy about the parts that were damaged).

Generally speaking, any oil that doesn’t meet the minimum specifications listed in the owner’s manual can damage the engine.

First thing:

The Mini Cooper (doesn’t matter if it’s an S version or not) is a small 4 cylinder engine, with 2 cam shafts, one for the intake valves, and 1 for the exhaust valves. There are 16 valves in total.

The older S versions had a Supercharged engine, and the newer ones use a Turbocharger instead. The turbo charged versions are very sensitive to engine oil quality, and using anything less than full synthetic is asking for trouble, if you are pushing the car hard for long periods of time, and not changing the oil frequently.

If the car was using oil on the trip, he might have had a lack of lubrication to the top end of the motor, which then caused the bearings on the opposite side of the motor from the timing belt/chain to seize, which then broke the camshaft in half as the motor tried to turn the camshaft anyway.

If its a Turbocharged car, Synthetic Oil should be changed every 5k miles, without fail.
If its a Supercharged or non S version, I would recommend Synthetic Blend changed every 7500, Synthetic changed somewhere between 7500 and 10k, or Conventional every 5k.


I really think that, in order to get answers with as much value and validity as posssible, the OP needs to try to get more accurate information from his co-worker.

Clearly, since the co-worker thinks that his car has six camshafts, he is not exactly a car-oriented person.
If the other information that he has reported to the OP is as off-base as the camshaft info, who knows what other mistakes he has made in relating information about the car?

I would like to know:

Does the Mini owner have maintenance records for the first 50k miles, before he owned it?
Which engine does this particular Mini have? (Assuming that the co-worker even knows the answer to that question.)
What does his Owner’s Manual state regarding the type of oil that is required for this engine?
What type of oil has he used?
How often has the Mini owner changed his oil, in terms of both odometer mileage and elapsed time?

As was pointed out this is an academic question, so please look at it from that perspective. As he has told me:

-I don’t know what size engine, but he did tell me it was a six cyclinder
-I don’t know if it is a turvo vs supercharged
-He says he had his mechanice change the oil just before he left with half & half
-It does state that he is to use sythetic oil in the manual and on the oil cover
-Per his statement he changes the oil every 6,000 miles and takes care of the car.

Off track the mechanic in Wyoming told him that he has seen these engines last to 600-700,00 miles if they are taken care of. He does not beleive he baby’s this car enough to get it there. This is not ment to to be an inditement against him. I think with all the things that go wrong on this car from the start that he has it in the shop enough for the regular maintence to be done.

This car alone and all his stories he gets from other mini driver would make me not want to buy one.

The answer to the original question, in this situation in question, NO.

If anything, not using synthetic oil caused this.

There is no such thing as magic oil. It ends up being a durability difference, which equates to a longevity difference.

There is no enhanced performance specification for “synthetic” motor oil, it has only to pass the same specifications as any other motor oil. Therefore the dealer mechanic is ignorant in his claim that “a” synthetic motor oil would have prevented this failure.

There are enhanced performance specifications that only synthetic motor oils have met, but there are no performance standards required for an oil to be sold as synthetic.

The Mini, if its the BMW Mini, being of European origin very likely specifies ACEA standards for its motor oil. Some of these are for extended drain. Some of these have never been passed by anything other than a synthetic motor oil. Not all synthetic motor oils pass.

“I don’t know what size engine, but he did tell me it was a six cyclinder”

Well, you have helped to confirm my suspicions, namely that your friend is terminally confused–at least as it relates to the car that he owns. While there are a few engine variants available on Minis, they are all four cylinder engines. As a result, I have to question whether this person even knows what type of oil he has used in the car.

However, assuming that the manual does state that full synthetic oil (not “half & half”) is required, and that he did not use full synthetic oil, then–yes, it is entirely possible to do some serious damage to the engine over the long term.

Essentially, he tried to “cheap out” on car maintenance, and he found out the hard way that “cheaping out” frequently costs more money in the long run.

Also, you can tell your friend that very, very few engines last ‘600,000 - 700,000 miles’. Most do well to get to 250,000 (something gives out, often the body or trans, or engine). And how could the mechanic possibly know this? These cars have only been on sale for a relatively short time, not the decades needed to roll up 600,000+ miles.

Oils have also improved vastly in the meantime. I think that it’s more likely that not using full synthetic would contribute to engine sludge, but I can’t imagine how it would contribute to a sheared camshaft.

Something had to happen to suddenly stop the camshaft, like a seized bearing, or the camshaft may have had a manufacturing defect. If the engine is really sludged up, it could indeed be an oil-related failure though. If the engine is clean, I doubt it was the oil.

There’s a lot of misinterpretation here since it’s obvious a camshaft did not shear.
Maybe a connecting rod or connecting rod bolts broke?

The odds of this being caused by not using synthetic is about zero. The odds of it being abused or neglected, either during the first 50k miles or afterwards, is much higher.

Without knowing what broke, how it was maintained, and how much oil was in it when this happened it will be impossible to make much of a guess.

Thanks to those who have answered with information.

This was presented as a philosophical topic. I know that we cannot control what people post on this public forum, but I sometimes find the input here condeming and predictable.

Not to sound like some posters, but some people’s need to condem others for their habits is not always needed. I am more depressed than anything that even a questions posted more for and as a theoretical exercise gets a lot of textbook responses.

I take the chance of ostricising myself for saying this, but it just kinda needles me. I have seen in the past that people love a change of pace is the topics and I had hoped this would be one of them.

Please let us know: what needles you? You posted a very specific question that requires lots of specific data to properly answer, data that we’ve not received.

The Mini Cooper is really a BMW, cars designed to use very high quality oils. They also have long drain intervals, dictated mostly by European environmental regulations, but continued this side of the ocean.

Using a blend (US spec) with less shear strength and high temperature stability of a full European synthetic can definitely cause engine damage; in fact it will void the warranty.

To make a European car engine last here, change oil twice as often as the manual calls for and use the oil specified. This is true for Volkswagens and other Euro cars as well.

I can’t comment on the specific damage here, but I am not surprised.

What you view as condeming (sic) could also be viewed as consternation and frustration as a result of being expected to answer a question while being provided little actual information, and what little information has been provided is highly flawed.

If you really want definitive answers to your questions, you first need to accurately gather all of the necessary information from your friend (possibly educating him about his FOUR cylinder Mini in the process), and repost the question once you have all of your ducks in a row.