Ask an expert

mine is mazda rx8(rotary engine) 2005 model..today i got it serviced by one of the well known mechanics in our area.. and from the receipt i found that they used a 10w40 semi synthetic oil and i got charged 55 dollars extra for the same.. i had a belief that rotary engines should be treated with mineral based oil alone.. every other places i get my car serviced have been using the normal 10W30 mineral oil… i am just worried wether its gonna make any harm to the seals or bearing …etc..????? when contacted i was not given a clear reply by the team who serviced it…just wondering wether i should go back to them and bring this to their attention...

Mazda recommend the non-synthetic engine oil so it is best to stick with what is recommended by the manufacturer.

Even though I would've thought the semi-synthetic oil would be ok (or better) the recommended oil is the safest option - unless otherwise stipulated.