Engine oil. Why the wildly opposing opinions?

[JimmyR]

I am restoring an '82 GS1100G. As my other bike is a Harley and all the Harley guys I know swear by fully synthetic oil that is what I use in my Harley. So when I went to Suzuki to buy oil for my Suzuki I was surprised to see that they didn't stock fully synthetic but only fully mineral or part synthetic. So I bought the part synthetic.

As soon as my local mobile mechanic saw the part synthetic I was in trouble! He gave me quite a lecture about how it glazes the bore and is the work of the devil. He told me only to ever use mineral oil or blight and pestilence will ensue. So I will return my oil and get the mineral!

There must be lots of opinions on this subject. I know a lot of folks here like diesel oil from Walmart. We don't have Walmart here! I asked my mechanic friend and he hadn't heard of using diesel oil in a bike before.

Does anyone actually KNOW what the differences are? Or is it all down to "what this guy told me once"?

[Steve]

The differences between "regular" and "synthetic" will depend on who you are talking to. I have heard that it really only takes a rather low percentage of synthetic oil to be able to legally call an oil "synthetic", so you have to read the label very carefully.

"Glaze the bore"??? I can't imagine why any particular oil would glaze the bore.

Where are you that you don't have a Wal-Mart? They are not the only suppliers of Rotella oil (the diesel stuff), you can get it at most auto parts stores or truck stops.

The advantage of diesel oil is that the formulation of automotive oils has changed over the last few decades. As more and more cars (virtually all of them, now) have catalytic convertors, you have to be careful to not pollute them with any additives that might be resulting from blow-by in the combustion process. So, in the process, oils have lost some heavy metals, like zinc, which really help with some heavy-duty cushioning in the bike engines, especially in the transmissions. Diesel-powered trucks, for the most part, do not have catalytic convertors, and, because of their heavy-duty ratings, are still allowed to use oil with the potential pollutants. The levels of zinc in diesel oil are just about where the automotive oil was, back when our bikes were new.

You can do a lot more reading about oils in general (maybe even some bike-specific stuff) at bobistheoilguy.com.

Regardless of which oil you eventually choose, one thing is universal about which oil you DON'T want to use.
Look in the API "donut" on the back label. Look at the bottom half of it, see if it says "Energy Conserving". If it does, DON'T USE THAT OIL. It has additives that will cause your clutch to slip. Other than that, pick an oil, stick with it, change it more often than you do the oil in your car.

.

[TheCafeKid]

I'd suggest not using your mobile mechanic anymore because his glazing the bore reasoning is a load of crap.

Most of us here that use traditional "dinosaur juice" use Rotella diesel oil because of the higher zinc content. I personally have used full synth as well as semi synth and frankly, I don't see any reason to shell out the extra dough. I have both read and been told that full synthetic handles hear better than Dino oil, so perhaps if I lived in an extremely hot climate I might go with it. But the only benefit is thermal breakdown doesn't occur as quickly. Considering that,if you're doing what you should, you change the oil every 2K miles give or take, I don't see this being a large enough benefit to outweigh the near double the price.

I run full synthetic in my 01 ZRX because thats what it's always had in it and there have been extensively documented cases of people that ran exclusively traditional oil suffering the dreaded cam lobe pitting that is a problem in more than a few of the GPz/ZR models while those who ran full synthetic have had markedly fewer instances of this. It may be crap, but I'm not gonna take the chance and Rotella synthetic isn't that expensive. Certainly cheaper than new cams and rocker arms or worse, a complete rebuild.

Everyone has their argument as to which oil they use and why it's better but one thing we will all agree on is that any modern "energy conserving" oil is absolutely NOT to be used in a wet sump clutch system like your GS. It will ruin the fibers and the clutch will slip. I once mistakenly added a quart of the TRUE devil oil and within 50 miles my clwas slipping slightly on the top end. I immediately drained the lot when I got home and it seemed to cure it, but a whole engine full of that stuff would have killed the clutch fibers. And to be honest from what I've read even the little bit I had in there wasn't good.

Anyway, stick with diesel oil, or synthetic, whichever you prefer. There are so many myths and BS assumptions that go along with either that are simply not true, but many old timer mechanics continue to perpetuate them instead of educating themselves on the facts. Bottom line is, for an air-cooled, wet clutch,motorcycle engine especially, the biggest thing is staying away from EC oils, making sure the Dino oil you may use has as high of a zinc content as you can find (and anymore either pure motorcycle oil, which usually costs more, or diesel oils are going to be the best for those) or a good quality semi or full synthetic (redline, Rotella, royal purple, etc)

[TheCafeKid]

I see Steve beat me to the punch

[tkent02]

Oil, shmoil.
Run what you brung.

As long as it's not energy conserving it's OK.

[JimmyR]

Thanks guys. I had a feeling that there was a lot of BS talked about this stuff. I'll just use what I have.

[Nessism]

As Steve wrote, oil is not the same as it used to be. Zinc and Phosphorus are high pressure oil additives, good for our engines, but the levels have been reduced (in the US) because they damage catalytic converters and shorten their life. Auto oils have in the range of 800 ppm and diesel oil 1200. The zinc and phosphorus in diesel oil has been reduced too in recent years - 2007 was a big change year for diesel emissions in the US. Bottom line is to get as much zinc and phosphrous in your oil as possible. Motorcycle oil is okay but expensive, that's why diesel oil is so popular with the GS brethren. Good stuff and cheap. As for synthetic, it's great stuff that both protects better in high heat conditions compared to mineral oil, and it also lasts longer to so the drain interval can be extended. It will not cause cylinder glazing (an amazingly ignorant statement).

[JimmyR]

Oh ok - now a lot of what I have read makes more sense. I don't mind buying motorbike oil. It's not like I have to buy it every week. I hate buying petrol - sorry, gas - though. I live in Australia, hence no Walmart. We do have Kmart, Coles and Woolworths though. And Burger King is called Hungry Jacks here.

[7981GS]

Here you go Jimmy: http://www.shell.com.au/home/content...ls_lubricants/

You can search for a distributor near you too.

Daniel

[Nessism]

You might want to search out Don or Pete here and ask them what kind of oil they use. I believe at least one of those guys searched out some appropriate diesel oils available in Australia a while back. Motorcycle oil is fine too, only it costs about 3 times as much money and doesn't protect any better.

Edit: searched out pete and found where he says he's using "Castrol GTX Diesel 15w40". He is from Queensland so diesel oil is obviously available there.

[hampshirehog]

Edit: searched out pete and found where he says he's using "Castrol GTX Diesel 15w40". He is from Queensland so diesel oil is obviously available there.

And that's what I use in the UK as well. Nothing against synthetic but I'm just tight and I change the oil every 10 minutes anyway.

We also don't have Walmart....though we do have Asda which Walmart have owned for a few years.

We no longer have Woolworths

[Suzuki mad]

I ran semi synthetic in my GS1000E like my modern day bandit and the clutch slipped like a &*%%$£"$%^&(**(^$%£$. Had to swap it back to mineral oil and change it a couple of times before the bike worked OK again.

I think its also why she blew a head gasket not long after.

[Shin-Ken 1074]

Oh ok - now a lot of what I have read makes more sense. I don't mind buying motorbike oil. It's not like I have to buy it every week. I hate buying petrol - sorry, gas - though. I live in Australia, hence no Walmart. We do have Kmart, Coles and Woolworths though. And Burger King is called Hungry Jacks here.

Hi Jimmy, as mentioned by team here you have a few options regarding oil and they have covered the important issues: don't ever use friction modified engine oil in a wet clutch system like our bikes and find an oil with a high zinc content.

To be 100% sure you are using an oil that will be safe for your wet clutch use an oil that is JASO MA certified.

As a bonus use an oil with a high zinc content.

To satisfy yourself about why these two points are important for our older air cooled GS engines just do little homework and you'll be better informed on which oil you might prefer.

Many owners use diesel engine oil and although it's a very good product are they are very happy with it there is one issue. The zinc content of many of the diesel oil brands has been lowered over the years and is not much higher than some of the standard engine oils, check the oil specifications to see the zinc %.

The good news is in Oz we have access to a fine product that is JASO MA certified and has one of the highest zinc % levels of any engine oil at 1480ppm compared to some diesel engine oils with a zinc level of 800- 900ppm, is cheap to buy and made here locally. Something to consider with diesel engine oil is many of them use a high level of detergent in the oil and this is not want you want in a air cooled engine when you are trying to gain the benefit of zinc.

I don't work for or am in any way connected to this product or the Company that supplies it, I just use the oil and it's been doing an excellent job for me and many other bike owners here in Oz. Once you have done your homework on it you might consider using it?

The oil to check out is:

Penrite MC-4ST Premium Mineral Oil 15-50

Don't be concerned about the oil weight not being 10W-40. If you use the Suzuki Oil Chart for Australian models, you will see this is the oil weight specified for use in our bikes here from minus 15 degree C up.

Hope this is of help, cheers.

[bdogginit]

Hi, I am restoring a 83 gs 750 es and l this may be a dumb question but when filling up the oil, I'm not sure how much to put in, it says 3200 ml beside the oil filler cap, but the level in the sight glass shows it being full before I put that much in and I am worried about overfilling. I'm not positive that the 3200 ml is refering to the oil capacity and want to be sure. any advice would be appreciated.

[Nessism]

Fill to the sight glass. Bike should be on the center stand, parked on level ground. Run the bike with a cold engine for a couple of mins's and then shut down. Wait a couple more mins's and read the level. Top off or drain off as needed.

The oil will expand when hot so don't check after a ride.