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Can I ask why semi-synthetic, not fully synthetic? Is there a difference in performance? I thought fully would be better than semi?



I use semi synthetic for a few reasons.

I dont do enough miles in a year to reach the service interval of 6000, but I do change my oil/filter every year, when I do change it, it comes out still pretty clean.
Its a bit cheaper than fully also.
It is not recomended to use fully synthetic untill the engine is fully run in, that can be quite a distance, on my old BMWs it was said to be at leasy 10,000miles.
I have herd that using fully synthetic could make the oil seals harden up, where as mineral oil keeps them soft, but they probably have additives now to prevent this.
Our engines are not exactly high reving.
Semi is good enough for me, but did you know that the term semi synthetic is decieving you may think it is 50% mineral 50% synthetic. in actual fact the synthetic part may only be 5%.