Synthetic oil, how often do you change it?

[Scurrie]

OK, this question has probably been answered a lot, but I could not compose a good search to get the answer. At my last oil change on the 99' 1100RT, I switched to synthetic oil. This was at the 12K service, done by a dealer who won't be working on my bike again (long story). Anyway, they suggested that I should still change the oil on the regular interval of 6K. In fact, even better at 3K, but definitely not more than 6K. Then I hear other people say with synthetic you can go 10K or more (one guy even told me he never changes it, just puts a new filter in at 10K and tops it off).

 

So what's the popular opinion on the board? Also, what is the best synthetic for the gearbox? I have heard good and bad about the BMW oil.

 

Thanks,

Scott

[SC_Jack]

If you want to leave it in for a longer period than BMW suggests in the owners manual, purchase some of those oil analysis kits where you send in a sample. Then, you will know for sure.

[W. Mazelin]

I change all the oils in the bike per the maintenance shcedule. They both have synthetic fluids throughout.

[leikam]

Everything I've seen says there's no benefit to changing sooner than the recommended 6k interval. If you want to squeeze the most usable life out of your oil, have it tested so you can calibrate your schedule to your bike as you ride it.

 

As for gear oil, you'll get a lot of opinions. I've been using Valvoline's 80W-90 gear oil and have no complaints. Most any gear oil will do just fine, including BMW's.

[No_Twilight]

I believe that synthetic oil has no benefits over regular oil (with the same API spec, current spec is SL) other than high temp performance. Our bikes are low temp applications. Friction inhibiting additives are the same in both and they are consumed with use. The amount of oil, type of motor internals, and gear ratio of the vehicle determines how soon the additives are consumed. If the engineers do their job, and I believe they do, they will specify an interval where there is some margin before the additives are consumed and friction wear increases. So I'd change it at 6,000 miles and I wouldn't waste money on synthetic oil. Another reason not to buy the more expensive oil: oil becomes contaminated with combustion byproducts no matter what type of oil it is. So you'll want to change it to get these acidic and corrosive agents out of there.

 

Just my opinion and I am the only one who is sure it is right.

 

Jerry

[KDeline]

O.K. once again, I have run Amsoil in my bikes for 80,000+ miles. The first time I ran to 18000 miles and the test said the oil was still good to go. That was with 2 quarts top up. I now go from 12000 to 15000 between changes, BUT I do change the filter every 6000 to 8000 miles. I did in the test run also. 110,000 miles on one and 97000 on the other, and no problems yet. I am not promoting Amsoil, just letting you know what I have been using.

[ShovelStrokeEd]

Jerry,

Your plan is sound but your data may be a bit off. Those who have tested, our own DB being one, have shown that the oil neither breaks down nor does it become contaminated beyond acceptable levels until well after the recommended 6000 mile interval. All of the testing, as I recall, was on relatively fresh motors. I think perhaps you are oversimplifying the situation with regards to the additive packages being the same between the two types of lubricant as well. I wouldn't be surprised to find the lubricating characteristics of the synthetic product to be higher as well. Something has to account for the improved fuel consumption many have experienced.

 

In terms of my plan, I'm moving everything to 10K mile interval. That has me changing the motor oil at 10K, transmission and rear drive fluids at 20K along with the consumables like air and fuel filters. Based on my experience with my 1100S, Mobil 1 Extended Life lubricants are working quite well for me. I do plan, next week when I hit the first oil change on the new lube, to send it out for testing.

[RichEdwards]

Mobil 1 changed every 6,000 miles. Since my dealer charges $78 for an oil change and he recommends every 3K, I save about $115 per 6K using Mobil 1, one oil filter, and by doing it myself.

[Blue Beemer Dude]

In terms of my plan, I'm moving everything to 10K mile interval.

 

Jerry may indeed be slightly off in his hypothesis, but I'm with him. People forget that the lubrication properties of an oil is independent of it's ability to trap and hold dirt and contaminants in suspension. This is why it gets dirty. So, even though it may not have broken down yet, the oil is still dirty.

 

As for you Ed, I think it's safe to say that you probably put more miles on your bikes in a year than the vast majority of us. So, all that great highway mileage, plus the fact that you're getting oil all good and hot and boiling off any water, lets your oil survive longer. Someone like me who rides only on the weekends, with occasional short trips riding to work for a total of about 6K miles a year; well, my rule is to change the oil every xxx miles or annually, whichever comes first.

 

So, the answer is: it depends. Mileage, time, type of riding. I think 6K is a fair compromise.

 

And besides, oil is cheap. You (and I disagree with you on this one, Ed) cannot change the oil too often. It's cheap insurance.

 

Oh, and I think synthetic is a waste of money unless you are experiencing high temperatures.

 

Michael

[Bruce Barrow]

Scott,

 

I tried a Valvoline 75-90 synthetic and the BMW 75-140 synthetic in the transmission and gearbox. The BMW is far superior in shifting, I believe the viscosity is the critical factor. My R1100 RT shifts better when cold than fully warmed up but there is very little difference since the switch to 75-140.

 

Good luck, Bruce

[ShovelStrokeEd]

Michael,

 

No argument from me. A typical riding day for me is about 8 to 12 hours in the saddle running top gear at between 4 and 5K RPM. Anywhere from 500 to 900 miles with the only shut down when I fuel up. Now, when I get to my destination for the week I might not put another 50 miles on the bike in 5 days. But come the weekend its back to that same thing. That is, for the most part, oil friendly riding.

 

Another thing I have taken into account is the number of auto manufacturerers who have extended oil change intervals. I remember when 1000 was a long time. That reflects better technology on both the oil side and the engine side.

[Paul Mihalka]

When multi-grade and synthetic oils were a novelty, anecdotal comment was the regular oils are really the low number thin oils with a additive that is a viscosity stabilizer. Supposedly the additives wore out and you ended up with the basic single grade thin oil. Like a 20/50 oil degraded to plain 20 weight. OTOH it said that synthetics are viscosity stable by nature and do not need additives to stabilize viscosity, they stay with the original viscosity range for life. Any comments?

[4wheeldog]

My experience with synthetic engine oils leads me to believe that one of the major advantages is better ring sealing. This accounts for the increase in fuel efficiency and the extended cleanliness of the oil.

A lot of oil moves back and forth through the rings into and out of the combustion chamber. The less this occurs, (Assuming adequate lubrication of the rings), the cleaner the oil and the less loss of combustion gasses.

The experience that sold me on the stuff was with aircraft recipricating engines. It is much simpler to quantify fuel efficiency under these circumstances, because it is easier to duplicate operating parameters. Efficiency was about 5% better, oil consumption was at least 50% better. Interestingly, the oil was recalled because it did not hold lead in suspension well enough, so many aircraft suffered stuck rings. I was using mogas (Regular unleaded auto fuel) so experienced no problem.

I am anal, so I still change my oil at or before the 6k recommendation. Good Luck!

[No_Twilight]

Jerry,... I think perhaps you are oversimplifying the situation with regards to the additive packages being the same between the two types of lubricant as well.

 

I do tend to be a simple guy. I think most problems are simple and get more complicated than they need to be for various reasons. I'll try to find the discussion that I read that was lead by an expert, chemist I believe, who works for an engine manufacurer. Anyway, his analysis convinced me he was an expert and indeed, he believes, based on actual testing, that modern oils are mostly a carrier for the additive package and if you stay below 300 degrees, the old fashioned oil carries the additives just as well.

 

It would not suprise me at all to learn that BMW puts enough margin in their design to go 10000 miles instead of 6. Especially since about 2/3 of my driving is on the freeway. Indeed, I let my last oil change go almost to 7 and didn't think a thing about it. After all, our oil sump on a 1100 to 1200 cc engine is almost as big as the oil sump on a 5000 cc mustang. Oops, I guess they're 4600 cc now. My truck is 5000cc with a 4.5 quart sump.

 

You certainly won't hurt anything using synthetic oils and you may get relatively cheap peace of mind. But none of my vehicles have ever had any synthetic oil in them. My truck currently has 135k miles and runs like new.

 

Thinking about the service interval, There's nothing I see other than oil that really needs to be done more often than 10000 miles (except rear tires). Maybe that's not a bad idea. I like round numbers.

 

I'll quickly admit that I don't know what the oil test tests but until I did, I wouldn't trust it. One man's opinion of whether an oil is OK may not agree with mine. For example, I'm a big believer in the new antifriction additives and I doubt the test will tell me if they are still present.

 

Cheers,

Jerry

[ShovelStrokeEd]

So, not to be contentious, but, you'll take the word of "your' expert but not "ours"?

 

I believe the company David and others used is one of the leaders in the field, specializing in fleet and aircraft work. They should have a pretty good idea of what they are doing as that is their reputation at stake. In terms of the additive package, that is one of the things they do test.

 

I just love it when people dismiss evidence that doesn't jive with their particular belief package as meaningless without having given the courtesy of reading the reports.

 

Believe what you wish. Change or don't. It really matters not at all.

[Marty Hill]

Gee, I change my oil every 200 miles. Is that why I've never had a bearing failure?

[Calvin (no socks)]

Marty, is that because you tow it the 200 miles?

 

I have synthetic in my lawnmower, I change it every 10 Years, if it needs it or not!

[David]

I believe the company David and others used is one of the leaders in the field, specializing in fleet and aircraft work. They should have a pretty good idea of what they are doing as that is their reputation at stake. In terms of the additive package, that is one of the things they do test.

 

I'm certainly no expert in oil, but this is a commercial lab that is one of the more widely used in the US. And additives certainly can be tested for. Other than that, I don't want to get into the oil debate. People would rather vacation in Gary, IN rather than change their beliefs about oil. At any rate, here's some results from oil in the R259 engine: click here. I have an even more complete chart for my own bike, if anyone is interested.

[eric1234]

Well, I have to admit that I'm too lazy to search out if it exists elsewhere. Can someone indicate the testing company of use. I'm sure that there are dozens, but (again) I'm just being lazy...

 

I'm in the midst of making a large change over in my auto from 3000 mile intervals (with dirt-cheap oil) to the 10000 mile interval with Mobil 1 (once I use up all the cheap stuff). Depending on the whole testing thing I might actually go 15,000 on the car...

 

So, I am interested to know who you all have been using for testing...

 

Thanks!

Eric