Different Oil Weight by Dealer

Car Info: 2011 Acura TSX 4cyl AT 27,000miles
I was at my Acura dealer for routine oil change and when I got home realized that they have been using 5w30 conventional oil in my car. The owner’s manual requires 0w20 conventional oil though out the year. I live in CT it’s winter during this oil change. Can this cause any long-term issues with the engine?
There is dirt sticking to the lower half of the engine block as if there was oil residue but could not find any visual oil leaks. Would this have happened due to incorrect oil grade?
I have been good with the oil change intervals at interval of 5-7K miles.

I called the dealer about the oil grade and they said they only carry that one grade of conventional oil.

Please advice

The dirt on the bottom is probably stuck in some oil that dribbled out when they loosened the drain nut - not an area for concern.

I think Honda might be very interested to learn that their own dealership doesn’t carry the oil that they want in their cars.

That said, I highly doubt the 5w30 is going to hurt anything but your gas mileage. Manufacturers started specifying low weight oils because they flow easier and nudge the MPG numbers up a little bit, which is a huge selling point when gas is over 4 bucks a gallon for someone who has to use premium.

And THAT said, I would still demand 0w20 because that’s what the manual calls for and I wouldn’t want any potential warranty denial issues should something happen to the engine.

You aren’t going to find a 0-20 in conventional oil. Acura doesn’t say synthetic just 0-20, but only comes in full or a blend. About $5 a quart difference. That’s why I do my own changes with Mobil 1 for the same price that Acura charges for the blend. They should absolutely not be using the wrong weight though.

Ditto what @Bing said.

I don’t think you can find a conventional oil that is 0-20w. My dealer never refers to oil as synthetic or not. They just assume that of you want 0-20w, you WILL get full synthetic and not a blend. That’s what my owner’s manual says too when it refers to the oil as just 0-20w. . It does not make a point of it. There fore, I agree with @shdowfax and would be some PO’d they did not use 0-20w synthetic or at least give you an option as Toyota does. I don’t see a long term damage done with using this oil…I do see a long term problem with trust as far as the dealership is concerned. I would use 0-20w from here on out. Blend is less then 10 to 20% synthetic and I don’t consider it any better then conventional oil for longevity. It only allows you to use the word “synthetic” IMho.

My car takes 5w-30, but newer models take 0w-20. They did that to increase mileage. Don’t worry. I would make sure you get what it says on the oil cap from now on.

One thing that you will potentially get with higher viscosity oil is more bypass of the oil while cold. With cold temperatures and thick oil, some of the oil may bypass back to sump/pump intake or around the filter. I assume that they did not change the filter for the higher viscosity oil. On my Hondas, I believe that the bypass goes back to the intake, and would assume it is the same on the Acura. So when starting cold, you may have less oil going through the filter and out to all of the critical parts. How much less? Who knows? But with a filter designed for 0-20w getting 5-30w pushed through the pressure across the filter is going to be higher, even with warm oil. Sounds like a pretty lazy dealership. Been around the parts department of enough Honda dealerships to know that they have all types oils. Should be the same at an Acura dealer. How do you know they are even changing your oil or filter? I’d find another place to have this done and fast. Only way to make sure it gets done is to do it yourself.

0-20 is a new grade of oil formulated for 10,000 mile oil changes now recommended by many cars… But only if you use this unique product. It’s always full-synthetic. Did YOU insist on conventional oil? I bet the dealer offered, even recommended the 0W-20 full synthetic, which is what your car requires to keep the warranty in force…

Honda branded 0W-20 is a blend:

Edit: or full synthetic:


Honda/Acura has only one filter. The same filter has been used for years on both cars specing higher weight and 0-20. The filter is the same and interchangable. I kinda doubt Firestone would be using a Honda filter, which may have been a red flag to the dealer for warranty.

We were up in Grand Rapids, MI when the car had only a few thousand on and it was down half a quart. I went to the Acura dealer for a quart of oil and all they had was synthetic blend 0-20 and didn’t think anything of it. Thats all they used. In Minneapolis though they carried the full synthetic Honda fluid. I wasn’t happy to pay $8 a quart for a blend, especially if it was 80% dino.

At any rate we have had the discussion before if its ok to use a higher weight when the book calls for 0-20. I guess I’m just for following the book and what was specified by the engineers. Whether its only to help the CAFE figures I don’t know but I know its not a problem anyway.

For $13 a quart, I don’t blame HP01 for being shy…He needs to find another place to have his car serviced…Hondas latest version seems to be full synthetic…


We stock honda 0w20 synthetic blend for the hondas in our fleet

So 0w20 is not always full synthetic

Irrespective of why it happened, suggest to address this asap and get the proper oil in the engine. The engineers at Acura know all the details of the engine and specified the required oil parameters for a variety of reasons. And most of those reasons are not ones you want to experience.

Yeah $13 at Amazon for blended is robbery. Handa is a little over $5 for blended and $6 for full syn, but you pay shipping. I buy my air and cabin filters and sometimes oil filters from them. Even the dealer is only $8 for syn.

If you continue use 5/W30 oil, I would continue to use that dealer throughout the warranty period on the engine. That way you can blame them for using the wrong oil if there is a warranty issue. I doubt that there will be a problem since 0/W20 is typically for gas mileage, but you need to CYA.

First, I think 0w20 is largely a CAFE fiddle. If I owned that Acura, 5w30 is what I’d give it.

That said, a dealer not having the right oil for the cars they service is grossly unprofessional! I don’t see much reason to continue using that dealer: being sloppy on oil might be an indicator that they play it “fast and loose” in more important areas!

Also to clarify: when a filter “bypasses,” it delivers unfiltered oil to the engine. It does NOT dump that oil back in the sump! That would make a dirty/clogged filter a “single point failure” for a car, an engineering no-no. A few seconds of bypass on a cold day is a non-issue so long as filtration kicks in after.

I would start using 0w20 oil starting the next oil change. If that means going to a different shop, so be it

it sounds like the dealer is stocking only 5w30, because they want to save a few bucks

That’s not the kind of place you want your car serviced. If they’re using the cheaper 5w30, versus the more expensive and correct 0w20, perhaps they’re also using cheaper and inferior parts for major repairs

Also to clarify: when a filter “bypasses,” it delivers unfiltered oil to the engine. It does NOT dump that oil back in the sump!

Designs vary but there has to be some level of bypass built in to regulate the system pressure. The pump is driven off the rotating assembly and pressure developed is a product of rotational speed. You will notice that the pressure gauge tops out at some rpm point.

Some designs have two bypass points; one at the pump where the excess is dumped directly back into the pan and the second to bypass the filter if it gets clogged to ensure oil gets to the critical parts even if unfiltered.

There is more going on with the 0w-20 oil…In Toyota and Lexus cars that require this grade, it allows 10,000 mile change intervals. The change interval drops to 5000 miles if any other grade of oil is used…So it’s not just for a 2% boost in fuel economy…The 0w-20 grade is a unique product…There is more to it than just the viscosity rating…