1993 Holden Commodore Oil light flashes

BERLINA304

MEMBER
1993 HOLDEN COMMODORE
158,000 MILES

The engine is a 5 litre v8. I revved it to around 5000rpm about 2 weeks ago and since then the oil light flashes at idle after about a half hour of driving. I have read a few different forums but each 1 has a different answer. The engine runs and idles fine and hasn't lost any power and the oil level is right on the full line. Could it be either the oils to thin?( But it was fine before and the oil hasn't been changed). I have also read that it could be the sensor or oil pump picking up sludge or failing? The oil isn't black, its a dark bronze colour. There was even a forum that said it could be big end bearings? There is no knocks or tapping. Worst case scenario, if it is bearings does that mean a full rebuild and is it an expensive fix? And should I be still driving the car

2 Replies

CARADIODOC

MECHANIC
33,873 POSTS

Any of the things you mentioned are possible. At the mileage you listed the bearings could have enough wear to allow the pressurized oil to run out through them too quickly resulting in low pressure. You may overcome that by using a thicker oil at the next oil change. The wear can be due to high mileage, which is not catastrophic, or it could be due to a momentary loss of oil flow that caused the bearings to be chewed up and rough. That kind of damage will continue to tear things up and is not likely to last two weeks. The bearings and crankshaft can be replaced but since the cause of the damage is oil-related, and oil protects many other parts of the engine, that is usually why engines are totally rebuilt. The crankshaft and bearings don't fail on their own. When they do fail, the cause is related to so many other parts and those are likely to have suffered damage too that will get worse quickly if ignored. A total engine rebuild addresses all of those things.

Start by having your mechanic check the actual oil pressure with a mechanical gauge. If it is okay, suspect the sending unit. If it really is low, try a thicker oil.