| Hi, on my 2000 748 i had the same problem in 1st,2nd and 3rd at ~7000 rpm, red light flickering. Measured the oil pressure and everything was ok. Changed the oil switch and still did the same.
I removed the oil and its colour was brown-caffe-latte. Practically i had water in the oil because of a cracked head on the vertical cylinder.
Hope you don't have the same problem... try by changing the oil switch | 
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