I've been changed my oil with Mobil 1 0w30, which I have been using for the last 3 months. I drove (all highway), 750 miles on a road trip. A/C for about 550 miles. average speed between 75-80mph. I left my car for about two days after I arrived. I drove it yesterday, went over a couple of speed bumps and the oil light illuminated. I checked the parking spot in which I parked no oil spots. I added another about 3.5 quarts to get the oil back up to level. So I am assuming that this car consumed this oil during this trip. This obviously isn't normal. Any suggestions? Also, I really don't know how long my oil was low for during this trip. I did changed my oil and checked the level the day before my trip. After I filled the oil beck to level I ahve driven the car around town for 200+ miles and the oil level hasn't changed. What other oil(s) do you recomend for my next long trip that wouldn't burn up like this?
thanks

 

I am not a big fan of Mobil 1 as I used to be, however of the best grades of Mobil 1, the 0W30 and one that I used, the 0W40, are a bit better. However, even then I had to use additives when I lived in Mexico, because I found I consumed quite a bit.

There is one in particular I like, and some others in this forum, and that is Castrol 0W30. It's a heavier 30 than the Mobil 1 and should not consume at the rate you saw it. I used this successfully without additives in Mexico and continue to use it here in the the United States. It's available at AutoZone or Pep Boys. That's the oil you might see us call GC or German Castrol. It was about $6 a quart last time I checked. I used the GC for my entire trip back from Mexico City to Florida with my vehicle fully weighed down with my and my father in it and still managed over 25 mpg without any oil consumption.

Two others come to mind. Amsoil 0W30. This another outstanding oil, but a bit more expensive near $10 a quart. Certain car parts stores carry it. I think I remember NAPA in New York state might carry it, but I have not seen it at Napa down here. Carquest stores are another possibility or just ordering it online.

Another one that is a bargain and a very solid oil is Pennzoil Platinum 5W30. About $5 a quart and available at just about any auto parts stores. This oil gets some outstanding UOA (Universal Oil Analyses) similar to the two above.

Also, try using an oversized oil filter for better flow such as the K&N HP-2009, which is available at just about any auto parts store.

If you're still getting problems you might have problems with your piston seals. For that I recommend Motor Oil Saver from Lubro Moly. It's available at most Napa Auto Parts stores. Bar's seal leak is also another possibility and I've seen that at a lot of auto parts stores, but I've had good experiences with Motor Oil Saver, not just in my RX300 but in other vehicles, particularly my girlfriend's 99 Ford Expedition, which used to chew oil with impunity.

 

dont forget,it could be the dreaded sludge problem.pull your front valve cover and see what it looks like.(I should talk,I never did check mine)

 

I doubt if it's your oil causing the problem but it is possible when you switch to synthetic on a higher mileage engine. If it were me I would want to eliminate that possibility first. Next oil change use regular 5w30 and monitor the consumption. You may also want to check you coolant and make sure no oil is in there. If it still consumes oil I would pull the valve cover and check for sludge as lexus114 suggested. If you are unfamiliar with the RX sludge problem do a search here, google or anywhere for tons of info.
If no sludge is found under the valve cover your oil consumption could be due to engine wear. How many miles? If this is the case I would try a heavier oil, or one the the oils made for higher mileage cars, or one of the many other products that help reduce oil consumption. A search here and over at Lexus Owners Club can find some posts on these products. Remember to do the troubleshooting before moving on to the solutions.
You are not the first to complain about oil consumption at prolonged highway speeds on the RX. I believe the end result was always sludge. A search on some key words like "oil consumption" here and over at lexus Owners Club will provide you with additional info.

 

I know about the sludge issue. But, why would that effect the consumption of oil? This is why I started using synthetic. I looked under the valve cover, and there was a little build up of sludge, not much, but enough where you feel bad for the RX. Every oil change I have been using motor flush to try and relieve this engine of the sludge. Another other suggestions? Thanks again for all you help.

 

that is a typical symptom of engine sludge.the motor doesnt get the proper lubrication.

 

Sounds like your sludge problem is not that bad from your description. Pictures I have seen of sludged engines show it really packed in there. You should find some on this site if you search. I would just use a good 5W30 oil next oil change that claims sludge preventing capabilities like Castrol GTX. I would lay off the motor flush also. This way you can determine if you really do have an oil consumption problem or are you causing it with your flush and synthetic oil.

 

LexMex mentioned Pennzoil Plat full synth 5w-30 which is what ive been using religiously in my 99 with the k&n hp-2009. When I first switched to this I was doing oil changes every 3k miles and it seriously cleaned it out and ran so much smoother/better. I have noticed that each oil change I would only pull out about 4.5 quarts but I do drive it pretty hard. Also, not sure if this has any bearing on your case but I remember hearing stuff about shearing of the oil itself with this engine which might explain why I'm always down 1/2 a quart.

 

well,this motor has very high oil temps.How often do you need to add oil unohoo??

 

never, by the time i do my oil change it has only gone down 1/2 a quart, but then again i do oil changes every 3k miles so.... I would imagine if i went longer I probably would have to add some in between oil changes

 

You know for higher constant RPM (highway) the oil useage could be higher because the rings are no longer seating properly from sludge build up, also the oil pump pickup may be slightly blocked and then the engine looses some lubrication which causes the rings to seize and loose more oil. Good luck my friend.....here is what a sludged engine looks like after scooping a coffee can of gunk out....

 

My Engine was a little better than that the last time I checked it. And when I did I took out about a half a soda can worth of sludge. What do you recomend as a additive to remove sludge in parts that I couldn't clean be removing the valve covers?

 

http://www.auto-rx.com/ is great stuff!
I know the time line is up on the sludge settlement, but I would still run it to a dealer and raise hell.

 

I would consider dropping the oil pan and taking a peak. If the pickup assembly is clogged you could starve the engine of oil.... Auto-rx would be a try, nothing to loose.

 

You are so right Thomas. When I took the lower pan off my DIL's RX just to take a look because if what I saw throughout the rest of the engine (have described it in the past), I was amazed at the small opening to the pick-up screen. It would be easy to clog that screen. I wonder why they restricted the opening. I don't recall seeing that on anything before.