jimzpsd

2006 WK with 125k 3.7, just did an oil change and now the oil light flickers on (along with the chime) at an idle. Driving its off, but at idle flickers back on. I'm thinking its the synthetic oil (too thin/slippery, 10w-30), or just the sending unit. Any common fixes here?

fishbone

You've got to get an oil pressure gauge on there to determine if you actually have low oil pressure. Any noises from the engine? Ticking? Knocking? Synthetic oil simply won't cause that to happen. Are you sure you put enough oil back into the engine? If you don't have any engine noise, it's likely you don't have an oil pressure issue. I would however be suspicious being that the gauge is getting a signal of the varying pressures as indicated by changing rpm.

dave1123

Try changing the oil filter. It's not common, but sometimes a filter will collapse internally and cause a blockage.

jimzpsd

If the filter is causing blockage, shouldn't the oil pressure by-pass valve engage and allow unfiltered oil to continue to recirculate? Its odd that this issue appeared right after an oil change, I still blame the synthetic oil, too light/thin.

wjlizard

Absolutely not the synthetic oil I run synthetic on every thing I have .from my tractor to my 4.0l wj to my Hemi commander to my Harley. Make sure you didn't pinch a wire and check your grounds the sensor could also be crapping out on you. If you've never used syn. in your vehicle before don't start now you are likely to start to develop leaks you didn't have before.on a side note the weight of the oil may be an issue, I'm not sure someone else can may be able to answer that but 10 - w30 sounds heavy. Sure it's not 5-w20. I'm just grabbing straws here

fishbone

From where are you getting this information? The weights and viscosity of synthetic oils are not different from conventional oils. They vary in both cases, however they are more consistent with synthetics. The basic difference between convention oils vs. synthetic oils is that the conventional oils breakdown almost immediately when heat is applied, synthetics do not. Thus, providing better lubricating qualities over a longer period of time. The use of synthetic oil is not causing your problem however, if you believe that it is, then get it out of there and go back to your old oil. Did you change the oil yourself? Or, did you take it for a flush and fill at one of those quick lube places?

dave1123

In a filter media collapse, the paper can block the return ports and cause the blockage. The overpressure relief valve just allows the oil to bypass the media if it gets clogged. This doesn't happen with quality filters because most of them have metal bands that contain the media. As I said, it's unusual for this to happen, but it does. If you change the filter and it doesn't solve the problem, all you're out is the cost of a filter.

IMHO, a 2006 shouldn't need oil heavier than 5W30. Oil viscosity is the same as conventional oils but synthetic flows easier. Synthetic cured the 4.0 rattle in my WJ. The only time I hear it now is on cold startup at below zero temps.

I'm thinking if you have a idiot light, you probably don't have a guage, do ya? I also don't agree that switching to synthetic causes leaks. On my 97 ZJ, the valve cover was leaking before I switched to synthetic and it DID get worse, but it was leaking anyway.

I suggest you change the oil pressure sensor.

fishbone

I agree if the OP has no engine noise it's likely a pressure switch. However the OP has never answered whether or not there is any engine clatter. It does not matter if the OP uses 5w30, 10w30 or straight 30. All of them have the same viscosity at normal operating temperatures and will not cause such a dramatic reduction in oil pressure (assuming the OP lives in a climate where temperatures are not still blow zero at this time of year). My GC idles at approximately 39 or 40 then jumps to 45 while driving. At what point does the low oil pressure light come on, 5? 10? I am not sure but what I am sure about is it would be a pretty dramatic drop. A drop that would not be caused by synthetic oil or 10w30 oil. Changing out the filter and or the pressure switch are both relatively cheap repairs that should be considered if you don't have the ability to check the actual pressure with a gauge.

jimzpsd

Update, the oil light hasn't come on at all in the last three days of driving and nothing has been done to it due to lack of time. There has never been any engine clatter when it did come on, so this weekend I'm going to replace the sending unit and move forward and will post back. Thanks guys.