sarah

is my engine oil pan and transmission pan supposed to be exposed underneath?

there's an undercover, but it only covers the bottom of the radiator area.

on my other cars, there's always an undercover to to protect the oil pan.

if there isn't supposed to be one in my RX, can I add one? speaking of the oil pan, I was tapping on the bottom of the oil pan the other day. why does it sound so thin?(again, I'm compared to my other car, which is a Mercedes... the MB oil pan sound really thick when I tap it)

Lexmex

Yes, they are supposed to be exposed.

I have some issues with road debris back in Mexico and the underside, but those same issues I have known have torn up undercovers and the underside on any other vehicle. Ask my uncle, he saw it quite frequently with vehicles he would work on. That's because things like tires, rocks, floods, etc. were common there, but you shouldn't have a problem driving on U.S. roads that are much better taken care of.

sarah

good to know that there was no undercover. I thought I lost it or something.

On my Mercedes, the undercover completely covers the bottom of the eingine bay, but it's plasitc. The US-spec cars get the plastic, but the German-spec cars get a solid steel undercover. I ordered the steel one from Germany and put it on. The steel plate MB undercover is almost 4mm thick!

AlexusAnja

Plastic I can understand, but metal is just unnecessary added weight. Also, unless you're really driving the RX off road where a large rock or big log might really impact the underbody and damage something, you'd probably not need the cover.

code58

Sarah- If you have a magnet check the oil pan on your Mercedes and see if it is actually steel. I know Mercedes has used a lot of cast aluminum, oil pans over the years and if it were cast aluminum, I'm sure it would sound a lot heavier, BECAUSE IT IS!. A magnet will definitely tell you.
The plastic undercover in the front is as much to direct air flow and let it exit properly as it is to protect anything. I have known of times that leaving the undercover off actually caused some heating problems because depending on the particular car and airflow design, the air can be turbulantly
disturbed and cause the heat not to be carried away properly. It may not be the case on a lot of cars but I know it is on some.
In addition Sarah, The underside of the engine and the oil pan are dependent on the airflow to carry away the radiated heat. With the underpan and especially the steel underpan the heat that is radiated is caught by the underpan, stored and radiated back at the underside of the engine instead of being carried away. The bottom of the car has a venturi effect (increased speed of the air from compression) that aids further in carrying the heat away. The underpan might work to a disadvantage in that respect. In all my years of driving (a lot-LOL), even on gravel roads at high speed, I have never damaged an oil pan. If your Mercedes does indeed have a cast aluminum oil pan, it's excellent heat transfering qualities could be nullified by the underpan.

sarah

thanks! I'll look into it... too cold to do it tonight...

come to think of it, while I was looking at the bottom of my RX300's oil pan
the other day, I noticed that it look relatively new and had a sticker with a
Toyota number on it.(well, sticker was too smudged to read) It was clearly
not the oil pan that came with my RX300.

I assumed that at some point my Lexus dealer replaced it under warranty.
If they had charged me, I would definitely have rememberd. The real
question is: why did they have to replace the engine oil pan?

code58

Sarah- I honestly don't have an answer for you. From working in the shop I can tell you it's easy to tell if the part has been replaced because factory production does not use the parts stickers that are on replacement parts. If you have no knowledge of it's replacement and you have no paperwork where the factory paid for a replacement on recall or otherwise, there is only one other explanation that I have. They either stripped the pan plug and the lube tech admitted it so the shop put on a new pan at their expense (doesn't happen often- the admitting i mean), or they damaged the pan while it was in the shop and replaced it and didn't say anything to you about. Yes, it does happen- it happened to me on a truck I had years ago. The mechanic that was working on it under warrantee left it up on the rack overnight without the safety on and the FRONT post bled down overnight and left the truck standing on it's nose in the morning. It damaged the pan and exhaust crossover pipe and they had to replace them at their expense. He did admit it though, BECAUSE I WORKED IN THE SHOP. Damage happens more often than you'd think in the shop and often if they can get away with it, they fix it up quickly (not always right) and don't say anything or just don't say anything and when it causes failure down the road, you end up paying for it. Sorry, but it does happen.

sarah

I just found out that's exactly what happened. I went through all the service receipts. On one of them, it showed oil pan replacement, showing a charge of $0.00. This was two years ago. It doesn't say much...just said that the drain plug was stripped, oil pan replaced, warranty. Since my vehicle was still under Lexus extended warranty, the dealer probably billed Lexus. I highly doubt that the dealer would pay for it themselves.

code58

That's cool huh? The lube guys strip the pan plug threads and then bill Lexus for it. No, the dealer is not likely to pay for something like that, I think I read that Lexus wanted over $600. to replace a pan because of stripped threads. Although with the upper and lower pan, Lexus is an easy pan to replace. I have changed my own oil all my life (don't trust anyone else to do it) and have never stripped a pan plug. I don't understand stripping plugs, tightening them without stripping is not exactly rocket science.