To make them change or not to change (the oil?)

[micheal]

Here is my dilemma. I was being stupid and expected the dealer to know the recommended oil for the Prius. Well when I was filing my last receipt, I was reading it and saw they had put in 10W instead of 5W.

After double-checking the manual that 5W is the recommended, I was first extremely irritated and wanted to take it to the dealer to make them redo it. (I have already had a devil of a time keeping them from overfilling). At any rate, the manual says using 10W is okay, but it should be changed at the next interval. The problem is this is my third oil change with the dealer and they have been using 10W each time (confirmed by previous receipts). D ue to just taking a long trip, there is about 2,500 miles until the next oil change.

Will another 2,500 on 10W matter or is the damage already done after 12K on 10W? I can't get to the dealer until Monday, but is it worth it in your opinion to take it back and force the correct oil? Part of me wants to go give them a piece of my mind, (I mean, this is a Toyota car!), but I don't want to be too hasty. What is the right course in everyone's opinion?

(Yea, I know if I had been less naive, this wouldn't have happened three times).

[Frank Hudon]

I'd be back when they opened on Monday morning. And when I left with new and correct 5/30 they'd know exactly who I was and not to ever put the incorrect oil in my car. I might even spray paint on the service bay door "5/30 for all Prius" in gold paint outlined in black.

[jayman]

What is the coldest temp in Lubbock TX this time of year? Or the coldest temp in January? Unless you're consistently below 35-40 F, I wouldn't worry about it.

The 5W-30 appears to be the "preferred" viscosity for Toyota VVT-i motors. The BP Lubricants/Castrol UK website offers a wide range of viscosity suggestions for this motor, depending on ambient temperatures, of even 15W-40 and 20W-50.

That said, a good synthetic is much more stable in use. A synthetic 5W-30 or 0W-30, a 0W-20 for that matter, will stay in grade. Most conventional oils will at first thin out then rapidly thicken.

As a practical note, the Mobil 1 line of synthetic xW-30 oils are considered "thin" 30 grade oils. Their test values fall at the lower end of the acceptable range, and the 0W-30/5W-30/10W-30 test almost exactly at operating temp. They do hold up very well though.

The only time I get picky about viscosity is the extreme cold up here. Especially at -18C or 0 F, only a synthetic 0W-30 or 0W-20 please.

[Frank Hudon]

it's the principle of it Jay not that it's harming the ICE but if the dealer can't install the recommended oil in it what else will they do "right"

[Bill Merchant]

[font=Comic Sans MS:23ca440769]Perhaps the best course of action, Michael, is to spend the next 2500 miles finding a dealer, or other Toyota service provider, that you can trust, and never give this stupid dealer your business again. And tell us who it is so others in your area can steer clear. At this time of year, that viscosity won't harm your car, even if it harms the dealer's reputation. You can get your oil changed anywhere, even do it yourself. Just keep your receipts for oil and filter every 5000 miles.[/font:23ca440769]