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Hi Folks - recently acquired a scrambler and looking for clarity on the best 2-stroke oil to use. Read a few articles on pre-mix v. injection 2T and potential considerations so hoping folks here could clarify.

Thanks
 

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Simple - if the oil injection is active, use injection grade oil in the oil tank - if the oil injection has been removed, then premix is mandated. As far as oil goes, each manufacturer claims their brand of oil is best, but I have used many different brands and have only found one that I advise people not to use - that happens to be Bel-Ray. Now this comes from racing two strokes. I developed the opinion that the only people who used Bel-Ray were people who liked to rebuild crankshafts. I didn't have that problem, but I didn't use Bel-Ray. I used damn near every brand of oil available including Oilzum. I had bikes with oil pumps and bikes using premix. You can premix any oil, but not every oil is OK in injection systems. But, any oil is better than no oil. I have resorted to using 4 stroke motor oil when nothing else was available.

Now I don't know what ratio of fuel to oil the people with Bel Ray were using, but this was proven by the boat motor manufacturers. The more oil you can mix with the fuel without fouling the spark plug, the more power the motor will generate and the longer it will last. The ignition system is the limiting factor. If the spark is not strong enough to cut through the oil, the plug will foul prematurely. I believe the people running Bel Ray were running 40 and 50 to 1 ratios. I ran about a 20 to 1 ratio, but because I ran an oil pump the ratio varied with throttle opening.

Having said all that I'll tell you what can happen if you mix incompatible oils. Back in the day, two stroke oil was basically two types - ash and ashless - this may have all changed today, but this is why you don't mix oil willy nilly. A guy bought a brand new 1972 Kawasaki F7 175cc dual sport. He left the shop I was working in on the new bike with the oil tank full of Kawasaki injection oil. About two months later be brought the bike in with the engine locked up and wanted it fixed under warranty. I was charged with the repair. I took the top end of the motor - it was so tight I had to press the piston out of the cylinder. The only damage was the piston & cylinder, but the crankcase was dry - no oil - looked like it had been washed with gasoline. I checked the oil line and it was full of oil (no indication of being run out of oil and pumping air) and the oil tank was completely full of brown oil (Kawasaki oil was green). I lubed the crankshaft (squirted two stroke oil on the rod and main bearings), installed a new piston & cylinder and proceeded to check the injection system. The oil pump was not pumping oil. The shop did not have a new oil pump on hand as we has never seen an oil pump fail. I took an oil pump off a floor unit, installed it and proceeded to bleed it. It was not pumping! I pulled the pump off and started the engine. The oil pump drive was turning, but I had seen the plastic drive gear fail and the shaft would turn, but it was not positive. I put a screwdriver in the drive slot to test the gear. I could not stop the shaft from turning, so the drive was not the problem. Now I was pretty quick about changing a pump, so I never pinched off the supply line from the tank. I just removed the banjo bolt on the line, held my fingers over the banjo eye to prevent a large quantity of oil from draining out of the oil tank and put the banjo in position on the new pump and tightened the banjo bolt. Yeah, I lost a little oil, but it was minimal. Was the new pump bad? Couldn't be! When I set up the floor unit I had bled the pump and IO knew it worked. Oh well, I got another floor unit and tested the oil pump before ripping it off to put on the bike being serviced. Installed it, tested it and it was not pumping either. What the hell? Now I got to pay attention to details. I pinched off the oil tank supply line and removed the feed banjo from the pump. I connected a banjo with an open ended hose and dropped the hose into a bottle of Kawasaki oil, started the engine and tried bleeding the pump. It bled just fine. I installed the original pump to test it - it bled fine and operated normally. The light went on and I took the clamp off the supply line on the oil tank. I waited for the oil. Over a period of about a minute I got 2 or 3 drops of oil. I should have gotten a half cup or more. I removed the oil tank to drain it since it wasn't coming out of the hose. I got brown oil, red oil, a yellowish oil and a little green oil. With the tank drained, I looked in the tank with a flashlight. The oil screen in the bottom of the tank and the bottom of the tank was covered with a grey slimy looking substance. I remove the strainer and the stuff on the screen was sticky like grease and had the texture of mud. I pulled the oil tank off a floor unit was the same color as the one I was working on and installed it, bled the pump and finished the service.

When the owner came to pick up his bike, the shop owner asked him when he filled the oil tank. The guy was honest and said he filled it just before he brought it in to assure it was full and we didn't try to blame him for running it out of oil. The the owner asked him how many times he filled the tank since he bought it. He responded every couple of weeks he would check the oil and top off the tank. What kind of oil? Two stroke oil. What brand? Whatever was on sale at Tractor Supply, Adolph's (short for Adloph Meyers a discount chain popular in the 70's), Sears or the lawn mower shop. The owner had me show him the mix of oil that I drained out of the oil tank and his first words were. "What's that yellow stuff?" It's oil - what kind have you put in there? H didn't know the brand, but he said he never put in any yellow oil. He had put in brown, red and blue in with the green oil we had in it. He did find the containers.

We turned the oil strainer and the four types of oil that was in the tank over to Kawasaki. Kawasaki informed us that there was a reaction between the oils and the ash that was in one oil solidified coating the screen and stopping oil flow. Kawasaki said the reaction was rare, but obviously not impossible. Kawasaki denied the warranty claim and the customer had to pay for the repair.

Therefore, don't mix oil types. Now if you want to change oil brands in an injection system, just wait till the tank is nearly empty and fill with the new brand. Two different oils are unlikely to have a reaction, but if you use a different oil on each fill you increase the likelihood a reaction might occur. The phenomenon does not occur with premix.

End of lecture.
 

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I use Opti II oil for all my pre-mix needs. I had a chain saw that I ran with other oil and it started to give me problems. I took it into a shop and they said they put fresh fuel into it and it ran just fine. Took it home and it ran fine until after I added fuel again. Took it back and we went through the same drill. They recommended the Opti II oil so I researched it and started using it too. For pre-mix, there is one amount added to one gallon which is guaranteed to work with any required ratio. I have used the same fuel mix in my weed eater, Mantis Tiller, chain saw and the 2003 Predator 90 ATV that we had gotten for the grandkids. All need different mix ratios and none of them have given any problems since I started using the oil. Over 6 years now.
 

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I recommend whatever oil is readily available in your area - I do not currently have any two strokes, but when I did I ran Klotz 2-Stroke Techniplate (blue label) for injection or premix. If all you have available in your area is Honda GN2, use it - if you have a Polaris shop nearby, use Polaris Blue - if you have a boat shop nearby, check out their injection oil.
 
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