I have a 1994 Lexus ES300 and I suspect that oil sludge may have developed in my engine. I would like your advice on how to approach the problem. I've changed my own oil using Mobil Synthetic 5W-30 quite regularly (usually every <3K miles) and just started noticing recently (159K miles) that the oil level on the dipstick is unusually high, past the level of the low-full mark. This check was prompted by noticing that my oil-level light flickers on and off on the freeway sometimes. How do I clean/flush the blockage that might be causing this? I've read about Auto-Rx and Seafoam but I don't know how safe these items are for my car and if there are other alternatives around that are better. I appreciate your advice.

Take your alve cover off and check for sludge.

Are you sure that is the oil level light? Or the oil pressure light?

The simple way to determine if you have oil sludge is to remove the valve cover as ASG14 said.

One of the place where you can add Seafoam is the crankcase (where you add the engine oil). 1/3 to 1/2 of a can of Seafoam is sufficient.

@BDSL: yes, it is orange and i checked it on the manual to see what it was. I started noticing it flicker over the Christmas break and it never did this before, only now that I hit 160K miles. I changed the oil once since it started happening and it went away for a couple months and has come back. However, the light only flickers when I am on the highway and going over 60mph. Decreasing my speed stops the light flickering and the light never comes on when I am in local traffic.

Would you say there is any harm in using seafoam on my engine? Also, I've never opened the valve cover on my engine and did a quick search. Could you point me to a good resource to help me along? I've never done this type of procedure on the car so I appreciate any help you can give. If I open up the valve cover I may replace the valve cover gasket and 3 spark plug gaskets too since I have noticed a bit of leaking starting to show.

Thanks for replying folks.

Highly unlikely that you have sludge. Your model year was not one of the cars prone to oil sludge issues.

possible that the oil pump is going..
synthetic oil will almost never sludge if you change it every 3000

thanks all. i am going to run some seafoam through the car gas, oil and vacuum hose this weekend and see if it improves it some.

i've only ever used synthetic oil in the car since i got it but maybe some small sludge has developed over time - not a lot - but enough to cause some kind of blockage.

if it is the oil pump, how much in terms of parts and labor is that going to cause me? i am a graduate student so money is tight and i'd like to know how much I may need to spend if this is the case.

that is good to know. though i have noticed that the older my car has gotten the blacker the oil has gotten everytime i change the oil, even at 3K. the oild isn't very viscous but if the oil is burning some in the engine, maybe some deposits have formed?

seafoam works wonders good luck

From your description of flickering oil level light only at high speed (even if the oil level is within acceptable level), it sounds to me you might have a circuit problem around the oil level sensor / connector. Check the oil level sensor, connector, and electrical wires. Make sure the wires are secured.

@BD: in addition to doing the seafoam, i will check that too. can you recommend a good manual to tell me the locations of those sensors? it might be worthwhile to get or borrow one for future reference. my 'ol girl is getting up there in the miles, afterall, so i want to have a good reference for further preventive maintenance.

The oil level sensor is located somewhere on the side of the oil pan. It should be something that sticks out from the side of the oil pan with a square flange and 4 bolts (might vary among vehicles).

For service manuals, try pdftown.com