python

iTrader: (4)

took this pic today...enjoy dicer

YODAONE

I use 0W-30 synthetic in a 99 LS400.(17 years ago the O.E.M.used 5W-30)

After 3,500 miles have not had to add a drop...suggesting ring sealing is unaffected.

Lexus uses 0W-20 in its late model cars...purportedly for improved mileage.

10W-30 is way old school...this was used by O.E.M.s in the early 80's.

Use 5W-30 or even 0W-30 Synthetic

Read the main oil blog on this forum for further explanation.

YODAONE

Comments received from Mobil (and why I use 0W-30) on another blog on point with 0W, 5W, 10W question.

This is for a 2000 LS400;

"Your inquiry has reached the Mobil help desk for US market oils in US market vehicles. I know that here, we would be recommending a 5W-30 rather than a 10W-30 for your Lexus. Typically, when dealing with hot environments, that second number on a multi-viscosity oil is the primary concern.

Whether 5W-30 or 10W-30, once the engine is up to operating temperature, they're both being measured as a 30. The main difference between the two will be the flow characteristics during a cold start first thing in the morning. A 5W is going to flow faster than a 10W, so your bearings and valve train which have been draining oil over night will receive a new coat of oil faster with a 5W.

I will be happy to refer your original question to our UAE desk for recommendations on locally available products.

Thank you for choosing Mobil,
Jim
Mobil Help Desk Team

If I can help further with this inquiry or with any other questions, please respond to this email or phone us 1-800-ASK-Mobil
If you would like to provide feedback on your experience with us today please email feedback@orderquestions.com

python

iTrader: (4)

ive been using 10w-30 since ive owned the car...over a decade...anyways it PASSED. I put a rear cat on it and it dropped from 73 to 41.

RA40

iTrader: (6)

Great! What were the readings?

dicer

Yoda they did fail to tell you the low number is the base number and then polymers are added that are suppose to thicken it up at op temperature. There are some engine manufactures that specifically state to not use multi viscosity oils in their products. One in particular is the Detroit 2 cycle truck type engines, multi viscosity is forbidden, I could not copy part of a many page pdf to show it. There are also some aircraft engines that are the same. There is good reason for them to specify only a straight weigh oil. That sales desk is quoting the Lexus requirement, if they did anything else and your engine crapped out they could be liable so they aren't going to say anything different. And the sales desk likely knows very little about engineering and how the oils are formulated.

Python did you replace the old cat? And your car looks nice an shiny, and happy to see the fenders aren't crumpled or anything.

python

iTrader: (4)

thanks bro appreciate the comment

@ra40 i gave the test results to a shop owner who works on my car..the nox was a little high but he said they would come down as the cat wears in. i wasnt happy with some other numbers so ill be having them look for other issues. i have another maf layin around..think ill put it on..the one i have on the car now is off a sc400 lol.
glad this is resolved! i gave the smog shop an extra 20 for putting up with my **** self during this process...im not a fun guy when i have issues with my baby