Thor Forums

[simidrm]

I personally use synthetic oil in everything I own (gas powered)expect for my pickup which has a cummins 6.7l and the motorhome and generator they get conventional 15-40.

The reason I say this is because I work on diesel engines everyday and the company I work for is nation wide and are now experimenting with using a semi-synthetic oils in there on-highway trucks and we have lost a lot of engines both cummins and detroit to main bearing damage and I have tried it in my pickup which I change oil in every 5k miles but when I went to synthetic after around 1200 miles my change oil light came on and I changed it again with same oil and less than 1k miles did it again so I went back to 15-40 and my change oil light hasn't came back on since and ive done about 3 oils changes at 5k.

This is just my opinion based on what I see on my own vehicles and the ones I work on at work and is not based on any brands or any data we receive from delaers who by the way still use conventional oils.