Sludge Or Sticky Valves?


New member
My wifes car has been kind of jumping at between 2 and 3rpm and its kind of annoying. I've seen the problem on a few other forums but for some reason they haven't posted the final solution.

First I thought it was the fuel so replaced fuel filter, cleaned injectors and upped the octane. Didnt help much.

Then I thought its the ignition system. Checked the resistance etc of dizzy and leads and checked the plugs. Still didn't help much.

Got to surfing the web and found a few people had tried these same procedures and even wasted money getting new parts. Found that post about a 4AFE sucking oil into the throttle chamber and sounded legitimate so I added some oil stabiliser (meant to help stabilise the viscosity apparently). WHOA did that freak me out! now it was happening really often and harder so changed the oil again. This time I put a half bottle of that oil flush through first. Replaced oil filter and added clean 15W40. worked a treat! Hardly any trouble with the lower revs now.

So quite what it wasIdon't know but I personally give the credit to half a bottle of oil flush (only half coz I didnt want the galleys etc clogging up or bearings coming udone). So I'll do one more closely spaced oil change in a few weeks to get any loose debris out and a month later I think I will use the other half bottle of flush as a preventative method.




New member
If you think your engine is gummed up with some kind of varnish / sludge left over from the use of conventional motor oils, etc., then it might be better to run some 5w-30 synthetic oil in it for a few oil changes to clean it out that way. I am assuming that 5w-30 is what Toyota specified for it. Synthetics tend to have better than average detergent packages in them and will clean out deposits left behind by conventional oil. However, they tend to dissolve it and clean it out at a slower rate than some of the quick fix flush products. The benefit to this is they are less likely to break loose a large chuck of deposits that then clog an important oil passage to a bearing, etc. The other benefit of this approach is you are using the SAE grade specified by Toyota, so there is little or no chance of damaging the engine by running oil in it which is too high viscosity and therefore does not flow well enough. Think of it this way, if your oil passages are already partially clogged up right now with old deposits, the last thing you want to do is try to send down them is some really thick high viscosity oil which may not flow well enough to get through the partially clogged passage ways.

I would not leave the synthetic oil in for too long because it is wise to remove the dissolved deposits with the used oil and filter relatively frequently when you are doing one of these clean out activities. 1000 miles might be prudent for a few oil changes then go to 3000 if things start to clear up a bit. Pennzoil Platinum is a reasonably priced synthetic that claims to have significant cleaning capabilities, so that might be a good choice if that is available to you. I have also had good luck cleaning up old engines with Mobil 1 as well. Once you have gone for 5000 miles on synthetic oil, and have cleaned the engine out, then if the car is really using a lot of oil due to wear of the rings and valve guild seals, then you could go to a 5w-30 “high mileage” oil which helps prevent oil consumption by having slightly higher viscosity and additives which help make the old worn seals swell up and work a little better.

The long term preventative approach to avoid sludge or varnish build up is to use synthetic oil on a regular basis and change it every 5000 miles or so.

Hope this helps



New member
One more thought, it would probably be a good idea to replace the Positive Crankcase Ventilation (PCV) Valve, if that has not been done in the last 30,000 miles. They only go for about $8.00 at my local Toyota Dealer Parts Department. They help keep the oil from becoming contaminated with blow by gasses, etc.


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