geckornr

This thread made me curious, so I went and checked my dipstick just to see where it was at. I had my oil changed in March for the first time around 1,100 miles. I now have 2,700 miles on the car and it appears it was overfilled in March:



My next (6 month) service interval is on Monday, so I’ll be bringing this up to them.

macmaster

^Overfill is really common. Don't sweat it.

arentz07

Yeah mine was overfilled on my previous oil change as well. It wasn't by much, visually, so I just ran with it. But yeah there's probably loads of owners out there driving around overfilled, and we never hear of these engines having issues.

I am with Mike on reporting it to the dealer, though. It really should not be this common.

Mine was a little below max capacity after this most recent oil change, which is probably better than overfilled...

macmaster

I'll explain exactly why it's common. It's basic Process Capability 101.

When engine oil is drained, there's typically anywhere from 0.25 - 0.75qts remaining (this is the consensus I found from the internet). The Toyota instructions is to refill the engine with 9.1qts. When you add these two up, you now have anywhere from 9.35 - 9.85qts after an oil change.

Now let's consider the dipstick. The volume between the two dots typically represents 1 qt. If Toyota considers 9.1qt to be the target, then these 2 dots represent 8.6-9.6 qts.

Are you starting to see the problem? The specification is 8.6 - 9.6, but the reality of the process is 9.35 - 9.85. Without empirical data I can't calculate the true mean and standard deviation, but you can already see how these two ranges don't overlap. We call this a poor process, and it's the reason why people are commonly getting overfilled dipsticks.

The question from this Process Capability Analysis is: Is the specification wrong (dipstick) or is the process wrong (instructions to operator/tech)? For a Kaizen company like Toyota that practically invented Six Sigma, it's extremely surprising they haven't addressed this so that the process would match the specifications.

EDIT: The conclusion from this analysis is that Lexus/Toyota will have an unnecessarily high number of unhappy customers who think the tech failed to properly change the oil. This increases their labor and materials costs and does not represent a lean process.

arentz07

Agree... something is off, and you'd think they would have figured this out by now.

It could very well be that the dipstick itself is the problem. We already know it is a strangely-hard-to-read dipstick. It's possible there are other oversights with its design.

Do you or anyone else happen to know if the stated "capacity" is the actual maximum for the system? I have tried Googling this to little avail. Seems like it's a case-by-case thing.

Ultimately all I have to go on is A) the amount of oil remaining in the bottle they returned to me, B) the "Quantity of Engine Oil" in the Vehicle Health Report in the Lexus app (which is just a green check for good at the moment), and C) the dipstick.

zcheng3

I just did my 10,000 mile service last month, and mine is slightly over the second dot. I asked the tech advisor how much oil they put in, he said that they use a pump/dispenser thing to fill the engine oil. This "dispenser" has auto shut off feature like the fuel pump at gas station. It will never overfill...

I am not sure if I should believe him

cyfi66

Big load of BS. You typically have to input the amount of oil into the dispenser and then it will dispense that amount. There is no way for it to know when the oil is at the right level inside the pan.

zcheng3

Thanks for the clarification. Ah... I will go for a different dealer next time. I have been regretting buying the discounted maintenance plan since the purchase. I will stay away from dealers as soon as my plan is depleted.

snowyblue

if its a dealer, then they prob have the oil pumps at the tech bays in the shop. usually you go to parts and say i need 9qts on pump 1 or something like that. then you pump the oil into the car. now the variable is the pump calibrated correct or did the parts person input the correct amount

RSColeman

Love these threads for the entertainment value. I mostly change my own oil and have been doing that since 1988. I currently have to change oil in Truck (Toyota T100 27years old), SUV (Toyota LC200), Car (IS500), Motorcycle (Honda ST1300), 2 boat motors (Yamaha 115, Tohatsu 20), Weed eater, Lawn mower. There are only 2 drivers in household and we both work from home. So only SUV actually makes mileage before the year passes. Everything else gets oil change once a year with exception of Weed eater and Lawn mower I do these at end of mowing season and in middle of season. Most everything runs on some sort of synthetic. I replace filter when I do oil and for truck/suv I rotate tires front to back. If a vehicle hits its mileage/hours before the year then that is when I do the change. The only vehicle that I have owned with engine failure was 1977 Ford F100 with 300 6 it lost rings in 1 and 6 around 180k miles that was back in 1995. Everything else has been traded in or sold to someone with zero issues. Almost everything was over 100K including previous motorcycles.
The IS500 is going to end up most likely in once a year catageory. The first change is going to be at 6 month mark (Nov). The every Nov after that. I will get Lexus to do first as it is free. After that I will be doing it and Mobil 1 or Costco synthetic will be what goes in, same 5w30 that I am putting in LC200 and T100.

DLPTony

When I learned to work on cars a century ago, the general rule of thumb was not to under or over fill the oil. If it’s over filled, the car will get used to it and will burn more of it. Obviously the engines are more efficient and adaptive than before, but I don’t know about leaving it over filled.