[quote]Any thoughts on why this would have started? Never had the light come on before in 6 years of racing. Engine has 204k and has never been opened beyond valve cover gasket!
How much of the inspection items can be done with engine in the car? Not really up for engine R&R in the garage.
What kind of rpms was the engine running when the oil light came on?
There’s a bunch of variables that go into OP, so it’s not Infantry simple. But there’s one clear truth…for all practical purposes there’s only one wear item in OP and that’s bearing gap.
OP is pump pressure minus resistance to flow. Obviously pump pressure is a matter of engine RPM, but resistance to flow is trickier.
Resistance to flow is a matter of the visc of the oil at temp, and the retriction to flow provided by the engine.
Restriction to flow. The oil has 3 routes, IIRC. To the galley, to the head, and to the oil pump’s intermediate shaft. A fair amount of oil goes to the head and the intermediate shaft, so a 20% loss of OP is probably a 50% increase in oil flow thru the bearings. The relationship between bearing gap and oil flow is a little tricky. A particle gouge in a bearing will reduce film thickness yet not reduce flow restriction. Reduced film thickness can lead to accelerated wear tho. Normal wear not only reduces flow restriction, but also wear accelerates because the worn bearings allow the crank to move off axis. The bottom line is that it’s a wear item and once it starts going it goes faster.
Viscosity. Oils are all different and you have to look deeper then the xWx weight band that it’s labeled. For example M1 15W50, a decent but not terrific oil, has a 100degC visc of 18-19 and Brad Penn 20W50, a terrific oil, has a 100degC visc of ~24 IIRC correctly. A thin oil Redline (20W50 100deg Visc 17) is going to run at a lower pressure then a thick oil (Brad Penn 20W50). Thin oils will drop pressure in worn bearings before thick oils.
There’s also the issue of the oil’s anti-wear properties. Most modern oils don’t have much in the way of anti-wear in their additive package. But smart oil choices will include the kind of anti-wear additives that allow bearings to better ride out an occasional light scuff. Anti-wear isn’t just for cams and rockers, it plays a role everywhere.
So what caused the OP light to flash? The combo of oil choice, oil level, wear state of the bearings, engine rpm, precise g load, and lack of oil control measures around the pump pickup.