All they have to do is send a sample into the oil analysis lab of their choice. That will tell the oil's viscosity. Look in the forums section. Bitog has entire section showing different lab results of different used and/or virgin oils.
Viscosity: Engine protection Vs. enhanced mileage
- Thread starter Sunshine Guy
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Carlostrece
$100 Site Donor 2025
What are the chances that a dealership would do that? It seems very unlikely to me.
A UOA is the wrong tool to find starting viscosity.
Do we have engine history on those running 0w-8 oil to say, 100k miles?
The Toyota/Honda dealership here has done it twice on warranty issues, according to what the parts manager said. The Toyota district manager made the request. For whatever the reason, according to the guy, it didn't result in a warranty denial in either case.
It will give you a ball-park zone. For instance, if you are running a 40 weight in an engine that has an oil fill cap that reads 0w-16, it will tell on you. That doesn't necessarily mean they would void a warranty, but they can tell.
Carlostrece
$100 Site Donor 2025
I agree that they could tell, if you were using 40 in a vehicle that called for 20. I'd never do that though. I could understanding if the dealership didn't like that.
What I would do is run 30 in a vehicle that called for 20. Would a UOA detect that? Maybe, maybe not. It would probably be a grey area with regard to detectability.
Even if it was detected, would they care? Probably not, IMO. Would they deny warranty? Probably not, IMO.
If you're going to color outside the lines, at least keep it near the lines, IMO.
As you know from many UOA’s posted here it’s not uncommon to drop a grade. So a car that specs a 20 grade could come back showing a 16 grade. A much bigger concern than going up a grade or two.
Having worked at a dealer for 12 years UOA’s were used to find contaminants like glycol. A VOA is the only correct way to find starting viscosity.
Yes. Especially with all the fuel dilution issues these days!
Carlostrece
$100 Site Donor 2025
Exactly. That's why I said using a 30 in a car that calls for 20 is probably undetectable in a UOA. I don't know why he gave me a laughy face emoji for saying that.
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If I bought a new vehicle, unlikely, I would use the oil that I thought best regardless of the manual, parts counter guy or service manager and take my chances. I cannot see going up a grade causing an oil related warranty issue.
Carlostrece
$100 Site Donor 2025
Agreed. Plus the dealership will not know if you go up only one grade. Even a UOA (probably) wouldn't detect that because when they do a UOA on a Xw30 grade oil, it will (probably) be sheared or diluted down to being like Xw20 VOA.
Also, would the dealer even care if they knew you went up one grade? Probably not, but irrelevant because they won't know if you don't tell them.
It's fine to go up 1 grade. Some say it's fine to go up 2 grades, but to me that seems potentially problematic. Just keep it to 1 grade up and don't worry, be happy. (Cue the Bob Marley music)
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Reported for posting math I don't understand.
I have a 1996 Chevrolet S-10 4.3L truck that has over 315,000 miles. It has always had 3k OCI. Probably unrelated.
Oh, what would be that tool, if not UOA? I'm the curious type. Thanks.
I would guess a virgin oil analysis.
Warranty repairs start with dealer or Carfax OCI. They don't have a way of knowing brand/viscosity unless they take your manual receipts to them. They will then have to prove the viscosity or oil brand was the cause of the failure.
I have never heard of a warranty claim being rejected for oil type/brand/viscosity, but only oil change interval. Have I missed these cases?
I have never either, but unless the parts manager is lying at my local dealership, an oil analysis was requested by the district mgr. twice since he has been there. Maybe it had nothing to do with viscosity, maybe he was looking for coolant or fuel dilution. Who knows.
Interesting. Now, I would change my oil to spec before I visited the dealer for my warranty repair.
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