Quote from: gsJack on July 14, 2017, 12:14:07 PM
Bought my 97 new and ran 10W-40 Spectro conventional mc oil for about 4k miles and then changed to Mobil 1 15W-50 automotive synthetic oil for about 60k miles and then went to Rotella T type 15W-40 conventional oils for another 20-30k miles.

Bought my 02 used with about 4k miles on it and assume that was with conventional oil.  I changed to Rotella T 15W-40 and went all the way to 100k miles on the Rotella T.  The 02 had 140 psi compression in both cylinders at 100k miles.

Awesome context. Thanks for that. First-hand experience.

Did you experience any of the shifting or clutch issues that I noted on the Rotella 15W40? Am I chasing my tail?

BTW I apologize for the threadjack.

If it wasn't a hundred degrees I'd be out riding instead.

Here is my take on oil.....
I use many places to buy oil from
I go to the most convenient place at the time to buy i
Oil
I always say I want semi-synth oil
I also say....Its oil for a GS5 so I am not paying more than £20 for it FFS!
I usually end up with oil from Motul but there has been other makes involved
I find it difficult to identify any significant difference between oil makes when fresh (at least in a GS5)
I find this approach to oil works best for me
I have never had any issues with any oil I have ever used.

And finaly.....I am not really interested in what oil others use and I dont really expect anyone to be interested in what oil I use.

Quote from: mr72 on July 14, 2017, 12:19:14 PM

BTW I apologize for the threadjack.

I don't mind at all!! I wanted discussion and I'm enjoying the replies. Please everybody, continue

somebody else  said  Motul   ,   I was in palm springs  last year  122  degree  with  Motul  300 V , gs500  never missed a beat  .

I currently have Honda's GN4 brand oil in my bike because it was the cheapest oil available at the dealer I was already at to get a crankcase gasket. That and for some reason, being a Suzuki dealer, they didn't carry any Suzuki oil. My reasoning being that the engine isn't making gobs of power. So, minute changes in oil shouldn't make that big of a difference, and I was already there. I haven't really had any issues with it so far, but I haven't gone a full oil change interval with it yet (knock on wood).

I'm in climate that likes to jump from one end of the weather spectrum to the other (sometimes in the same day), should I be running full synthetic?

The GS5 engine was designed 3 decades ago and it ran reliably 3 decades age on the oils that existed 3 decades ago. Nothing has changed in the intervening years including the service interval so why bother with modern expensive oils and pay for all the hype?

Maybe if I was racking up huge miles on a regular basis or running in a hot climate I might go for something more advanced but for normal use......nah.

Of course if it was some high tech, liquid cooled, fuel injected catalysed, high reving, close tolerance affair with hydraulic valves it would be a different matter.......but its not!

Started using full synthetic Fuchs 15W50 due to Queensland being very hot in summer, however paying nearly $70 AUD for 5 litres seemed excessive.

Now I use Penrite semi-synthetic HPR Diesel 10W40 with a full zinc package so I could use the same oil on our S40 with its flat tappets. I found that going from 15W50 to 10W40 did not make the engine run hotter at all. There was an image of a motorcycle on the label meaning that it did not have any friction modifiers.

I think the best way to get the cheapest oil is not to buy oils that are made specifically for motorcycles as they seem to have an automatic price increase for no apparent reason. I'd just get a good quality 10/40 diesel oil that has 1300-1600 ppm zinc, and doesn't have any friction modifiers, find an oil then email their tech department to check.

I've tried a few in my 450 over the years... initially I ran Shell something or other motorcycle oil... sure it was good but it was ridiculously expensive given I service it every 5000km's.

I tried a Motul fully synthetic oil and all it did was develop leaks it never had before. It also seemed to  evaporate... I was constantly topping it up beyond what I saw leaking.

I tried a Castrol GTX diesel oil and it seemed ok but when comparing against what's available in the US (Rotella) it didn't really seem to have all that much zinc etc.

I finally settled on Penrite HPR 15 semi-synthetic 15w50 diesel oil and have never looked back.

Most of the guys I ride with are also on older GS/GSX models and have had similar experiences to me and a significant number use the Penrite also.

If I was in the US, I'd stick with the Rotella for sure.

Modern fully synthetic oils are just not necessary in a bike like the GS unless of course you're racing, and then it's a whole different story.

Interesting that Motul works OK. I found in the SV650 motor ( or at least the Cagiva Raptor 650 version of it) that it made the gearbox sticky. I used Motul mostly in my race bikes except the ER6N which also didn't like it ( gearbox again). I thought the SV and GS500 gears were of a very similar design so it does surprise me that it works well. The sticking may be other than the gear dogs.
Recent tests have shown that high zinc may not be a good long term choice for most engines and particularly aircooled motors because of local very high temps. I was a big fan of Pentite full zincs for my cars, but have gone back to low zinc. In my Rodeo diesel, full zinc definitely improved my fuel economy ( noticably), but doesn't seem to make much difference in the Subaru.
I will use Penrite 15 or 20 /40 low zinc, JASO oils for the GS. I don't have real low temps to contend with. ( doesn't ever go below zeroC here).

Quote from: peteGS on July 17, 2017, 12:37:32 PM
Modern fully synthetic oils are just not necessary in a bike like the GS unless of course you're racing, and then it's a whole different story.

Not necessary ... but again, it can't hurt, right? If a modern synthetic oil results in less wear, smooth(er) shifting, correct clutch engagement, etc., then the only thing not to recommend it would be cost. In my case the Rotella is cheaper than a conventional "motorcycle" oil from a MC shop, so it's a win-win.

I kind of figure a big part of the heat in an air-cooled engine is caused by friction, and reducing friction could reduce heat. And the thing most likely to break a properly-maintained GS500 engine, I'd guess, besides being an idiot and over-revving it or other squiddishness, is to let it overheat. So less heat == less likely to grenade, and therefore spending another $5 per oil change (which being honest is probably once a year for most of us) vs. the bargain basement for Rotella synthetic sounds like it's worth it to me.

What's not worth it is paying too much for inferior oil just because you bought it from a MC shop. IMHO of course.

mr72     words  of wisdom