matthewlsw

I have an '03 RX300 with 230K miles. Has never had any issues but when I hit around 215K the amount of oil I would drain during a change would be less and less each time. I started decreasing the time between changes but it got to the point where I would be changing oil and filter every 2.5-3k or so, which was a lot of work and costly. I am using Mobil 1 synthetic high mileage with an K&N filter.

The problem is, even when I would only get 2 quarts back the dipstick had shown an acceptable oil level. So when it is low, it still shows a good level and this is baffling me. To combat a potential cause I replaced the PCV valve but that hasn't made a ton of difference.

For now I am just adding a quart every 1500 miles or so instead of changing it constantly. But if anyone has any insights as to why the oil level shows good even when low I would love to hear them!

Lexmus

When you add a quart of oil after 1500 miles, what is the level on the dipstick before and after adding the oil?

thomas1

Sludge, probably bottom of pan full. causing false readings.

salimshah

I am lost. What exactly do you mean by "2 quarts back" -> Do you mean when you drain, and measure the oil, you measure it to be 2 Quarts and you are calculating that that you have burnt 3+quarts. [it takes 5+ quarts for oil change]

The other confusing part is that when you read the dipstick, it shows you full, and since you do not trust the dipstick mark, you add a quart now and then. When you add a quart when the dipstick shows full, then the additional quart should make the level go higher than full without running the engine.

Thomas as always is right about gell [which takes up volume] to give false level as the capacity is changed.

I check the oil level after 10 minutes or so after the engine has been shut off As this gives time for the oil to works its way down.

Caution: There is need to have a volume of oil but the level [dip stick only tells you the level] has to be correct. What I mean is that if you go by capacity (volume) and you have massive sludge, your crank shaft may be sitting in oil.

Salim

Fit1too

Wouldn't you notice some sort of thick substance/sludge oozing out of the drain hole when you take the plug out? It doesn't look like it's hard to drop the oil pan. Is it a big deal to drop the oil pan?

matthewlsw

The stick shows exactly the same level which is messing with my brain.

matthewlsw

That sounds like a possibility, any experience cleaning it out?

matthewlsw

Yes like when I drain all the oil out and put it in the 5qt container that the new oil came in, it only fills up the container to the 2qt mark.

And correct, I am not trusting the dipstick because it shows a normal level even right before an oil change when I only get 2 quarts back so I know that it should have read very low.

It is sounding like I'm having a sludge problem since it always reads the same level, I will try to research how to clean it out and prevent it in the fiture.

salimshah

hmm .. you should not ignore dipstick as it shows the level of oil. If you fill above the mark then oil level starts going above the level it needs to be. If you fill above the level breather tube stops functioning.

Salim

Lexmus

Buy one of those boroscopes for your smartphone and put it in the oil pan drain hole after draining the oil and let us know what you see.

Here is one

matthewlsw

Just ordered! I'll keep you posted!

Lexmus

You also might want to do an engine flush prior to draining the oil to kickstart any sludge removal. I have never done one, so do not have a product recommendation.

I have added marvel Mystery Oil to engines in the past, which has a cleaning effect, but not nearly as strong as a flush product.

carguy07

Not trying to be jerky here, but based on the symptoms this can only be user error.

2KHarrier

Is there any chance it has the wrong dip stick?? Sounds idiotic, but it's possible. In regards to dropping the pan, I dropped the oil pan on my RX and posted pictures. It's an easy job and a good idea with higher mileage cars. Nothing wrong with a clean oil pan.

There's got to be a boat load of sludge in the pan. Not to mention in the heads as well...

carguy07

The wrong dipstick won't do this and sludge won't either.