In the past couple of weeks i had some problems with spark plug in cyl no 3 , it was getting oily and started to misfire. This has happened 5 or 6 times and i had to swap it with a new one each time up to the point that my stock went out and i had to clean each plug and use it again. Funny thing is that the symptom was happening when i was cruising in low speed and not when i was revving hard.
At first i was afraid about problem in cylinder or piston but after a discussion with JKBsprint (aka John) he told me that probably my oil was shot dead and should change it. To be honest , oil was a mixture of Selenia Synthetic and noname low price 20/50 which might cause uneven pressure to oil chamber. the reason was that at some point i decided to use good Selenia oil for better performance but engine didn't like it and started to consume it like 2-stroke. Of course selenia is expensive and i couldn't afford 20 euros per week just to be burnt so i started to fill the missing oil with cheap 20/50 wich was thicker to minimize loss.
Well , trick was success, oil consumption was minimized but Sprint ddnt like it either because i could see pressure below 4 even in cold weather , engine was rough and now after 1000k miles i had that symptom with plug no 3. John told me that due to design flaw cyl No 3 is close to oil stick and pressure is much higher there so if the oil is no good it might flow in.
So when i asked him about oils he suggested Aral 20/50 as a cheap mineral oil which boxer engine loves or Aggip and Motul ( both semi) if i wanted some better and more expensive. i decide to go to a big Supermarket ( Carrefour hypermarket) and get me a 4ltr of Arai 20/50 at 27 euros. Not a bad price for 4 litres when a Selenia Red 1 ltr cost at about 20 euros.
I went to my mechanic Takis and we changed oils along with filter and a fresh set of plugs. I decided to try Champion plugs instead of Golden lodge just to see the difference (none so far) .
So far i am very pleased with Aral , oil pressure when cold is 4 psi and when i rev it can climb up to 5 . Also engine runs smoother and i don't hear any harsh noice so it seems to be a good choice . Only thing thats left is to see how long they will last before they become soup after hard revving but i recommend them as a cheap but good oil for boxer engines.
Sprint 1.7 '85
Last edited by Greek; 14-04-10 at 11:34.