I can buy oil for my 2 strokes scooter from 60NT for a litre all the way up to 500NT for synthetic oil. Mineral oil is generally no more than 150NT and the cheapest synthetic oil starts at about 300NT. I used to be able to buy a cheaper one for 200 but it’s no longer available.
For the longest time I was buying synthetic oil made by Repsol. It’s called “Synthetico” and it costs 300NT. For my NSR, I often even bought the “Competicion” kind, also made by Repsol but at a very high price of 500NT.
I use 2 litres per month on average. If I buy the cheap stuff for 80NT at the gas station, I’m at 160NT per month. If I buy synthetic oil, I’m at 600NT per month. Over two moths only, I can save 880NT. This said, I can buy a new piston, sleeve, rings, crankshaft bearing, and all necessary gaskets for a whole new top end for 960NT and have it installed in three hours max. If you get the mechanic to replace it, you’re looking at 3000NT MAX. I can save 3000NT in oil money in 7 months. I can’t see my engine dying within 7 months even if I used the cheap oil. So why would I bother with synthetic oil?
I do notice the bike smokes a tad more when it’s cold and the exhaust has a stronger smell to it but other than that, I do not notice a difference in performance at all with the cheap oil.
Is there any reasons why I should go back to using synthetic?
And how about four strokes? The money difference is less over time as the bike uses less oil but the question is the same; which oil should be used?
Finally, is it true that mixing both synthetic an mineral oil is bad for the engine?