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Posts: 386
| Hey guys -- I appreciate all your feedback on my boat questions and have another one for you . . .
My engine is a little old -- a 1990 Johnson 90hp, oil-injected, but is still in excellent condition. I thought I might switch over to a higher end synthetic oil to prolong its life, reduce smoke, etc. Do I need to completely empty the regular 2-stroke oil currently in the oil reserve or is it ok to mix them?
Thanks for the advice, as always. |
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Posts: 32959
Location: Rhinelander, Wisconsin | The new synthetic oil you choose will should list on the bottle if it's OK to mix with other non synthetic oils. There's several 'blends' out there that are basically a mix of synthetic and non synthetic, but I'd abide by what the instructions on the bottle say. |
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Posts: 311
| To be 100% safe, drain all the old oil out before adding new oil. I had non-synthetic in my 2-stroke sled and switched to full synthetic, the bottle said you could add this to all oils without any harm. Well, I did and 40 miles later the engine decided to let go. Took it to my dealer to have it repaired and when they got it apart they said the oil was just like water. I have learned my lesson with mixing oils, I will drain my oil tank 100% from now on no matter what the bottle says. |
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Posts: 386
| Thanks guys! Always want to be safe, so I drained the oil (pretty messy) and added the new.
I look forward to seeing if there is any noticable difference in performance/smoke . . . |
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Posts: 742
Location: Grand Rapids MN | It's always good to contact the manufacturer for recommendations but they will always error on caution and say drain it. That's a good idea anyways if you want to start seeing the effect of your oil switch. But I'll throw a little 'casual oil info' out there for your reading pleasure. Your conventional oils are called Group II oils which is nothing but crude that goes through a hydrotreat process to remove some "impurities." Most synthetics you buy are a Group III oils which is a conventional oil (crude) that goes through further refining called Hyrdocracking. This goes a step further and 'breaks' some of the unwanted molecular chains (aromatics). They are essentially the same product just further refined. There are Group IV oils which are PAO's and those are man-made. These are more expensive to produce so fewer companies still use this for their standard synthetics oils. Even PAO's can be mixed with your conventional. There are instances where something goes wrong after an oil switch and it makes you nervious about doing it again (for a good reason), like in Joe's case, but it's usually something else that went wrong and not the change in oil. Just make sure what you choose is made for a water cooled 2-stroke and not air cooled because of the difference in ash content. Water cooled are generall ashless or very low ash oils. You will notice a difference right away if you get a higher ash content oil, seen it first hand in a friends boat. Missed bad on take off and didn't want to start very well. Luckily caught it early and cleared up over time with the right oil.
Hope this helped some what..... |
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