[gto4sun]

I am a new owner of an 81 308 GTSi. My oil pressure light went on and I only had standard 20/50 oil in my garage. the car was low 3 quarts. About two weeks later I was driving down the freeway and then my "slow down 1-4 cyl" light went on. I was told that mixing standard oil and synthetic may have fouled my plugs and that is what is setting my light off. I plan on changeing my oil and plugs. if this doesn't work. what could be the problem? PS the car feels it lost some of it's bottom end

 

[Pete04222]

I think (not sure) that the slow down light is an indication of a partially clogged catalytic converter.

 

[Stradale]

Mixing synthetic and mineral oil is a NO-NO. It will cause sludge to be formed. Drain and flush your engine with 'flushing oil' before filling it with synthetic again. Do flush.

 

[gto4sun]

I changed plugs 1-4, all but one looked ok. one plug looked a little wet. I also flushed the the crank case and put in 20/50 synthetic. I went for a test drive and the light didn't come on. I'll change the other plugs tomorrow.

 

[Stradale]

I hope you get the baby on full song again.