QuestionSir, The oil pressure light on my daughter's '97 Plymouth Breeze comes on(oil level okay) only when it comes to stop. It has 130,000 miles on it, bought it as program car, my wife and I drove it, then my son and now my daughter. Has been a reliable little car. Also engine is not making any unusual noise. Have had oil sending unit replaced before. Can you help me out? thanks, Mike.
AnswerHi Mike,
This is fairly common with all makes/models. Your idle rpm may be a little on the low side which means the pressure is going to be low enough to turn on the light after the engine warms the oil, which also lowers the pressure a bit. The actual minimim oil pressure is 5 psi so if you wanted to check this out you could have it measured with a gauge at a shop or buy a gauge and substitute it for the oil pressure light sensor located next to the oil filter.
But in my experience I would not be concerned for the moment, but rather the next time you change the oil increase the 'weight' by one step*, which increases the viscosity and thus will raise the pressure at idle so that the light will usually not come on anymore. The only time you really have to be concerned is if the light comes 'on' when you are driving and the rpm is higher than about 1,000 rpm as that could mean there is insufficient oil reaching all the moving parts.
Roland
*If you have been using 5W-20 try instead 10W-30 for example. Also it is the case that if you are using a synthetic oil that too will have a lower pressure at a given temperature and rpm than conventional oils. But again, I would not be concerned except as you note were it to come on when you are driving and at rpms above 1,000.
