Carbon deposit on "baffle" under engine oil fill cap - used 2015 Toyota Highlander

[NissanMaxima]

Hi all,
I'm looking at buying a private party 2005 V6 Highlander with 125k miles. Two owners with long history of regular maintenance including regular oil changes, fluids, etc. since new. A lot of maintenance at dealers, and some at independents as well as a few oil changes at quick lube places. Everything looked pretty good until I opened the engine oil cap and on the "baffle plate" (sorry it that's not the right word) was a rather thick layer of black hard carbon deposit. It wasn't completely hard and could be dislodged but definitely hard and not slimy sludge. My corolla I eventually sold at 260k didn't have any of this present. Just wondering if this is normal or sign of something concerning.

 

[Furious]

This is pretty normal for engines with baffle plates, the oil just kind of sits there and bakes and doesn't have any oil flow to prevent it.

Only real way to know how clean the engine is though is to pull the valve cover.

 

[SubieRubyRoo]

Pull a UOA from the dipstick and send it to a lab that does oxidation. No soccer mom is going to be using M1 FS 0w40 or any other engine oil with esters & ANs, so unless they just did an oil change the test will tell you if the oil’s getting too hot and absorbing (adsorbing? I’m no chemist) oxygen and causing the deposits.

It seems Toyotas either by OLM or by heat/blowby tend to have a good percentage that make varnish and carbon deposits, so, caveat emptor IMO.

 

[Brian123]

Hi all,
I'm looking at buying a private party 2015 V6 Highlander with 125k miles. Two owners with long history of regular maintenance including regular oil changes, fluids, etc. since new. A lot of maintenance at dealers, and some at independents as well as a few oil changes at quick lube places. Everything looked pretty good until I opened the engine oil cap and on the "baffle plate" (sorry it that's not the right word) was a rather thick layer of black hard carbon deposit. It wasn't completely hard and could be dislodged but definitely hard and not slimy sludge. My corolla I eventually sold at 260k didn't have any of this present. Just wondering if this is normal or sign of something concerning.

Sounds like this car has had the cheapest oil put into it, if you really want this car, get the Valve Cover popped and see what is inside? Then you can make up your mind!

Kind of seems like you should have kept the Corolla!

I would be concerned, is it normal, yes it is for a car that has had cheap oil.

 

[Furious]

Pull a UOA from the dipstick and send it to a lab that does oxidation. No soccer mom is going to be using M1 FS 0w40 or any other engine oil with esters & ANs, so unless they just did an oil change the test will tell you if the oil’s getting too hot and absorbing (adsorbing? I’m no chemist) oxygen and causing the deposits.

It seems Toyotas either by OLM or by heat/blowby tend to have a good percentage that make varnish and carbon deposits, so, caveat emptor IMO.

My Toyota has a 1MZ-FE which is a known oil burner/sludge monster. However mine is clean due to proper oil changes and PCV valve replacements during it's life. However the baffle plate is coated with some baked on oil, nothing major it is just the way it is.

 

[NissanMaxima]

Correction... 2005 Highlander.... I should add the valve cover gasket is leaking a bit. I sort of doubt cheap oil was used. It was serviced at Toyota dealers a lot and owner says hybrid oil used. There will be no way to have the valve cover removed to look inside before purchase. If deposits/sludge is in the engine, wouldn't a switch to full synthetic like Mobil 1 help to start cleaning it out?

 

[Trav]

It sounds normal to me.

 

[SubieRubyRoo]

Correction... 2005 Highlander.... I should add the valve cover gasket is leaking a bit. I sort of doubt cheap oil was used. It was serviced at Toyota dealers a lot and owner says hybrid oil used. There will be no way to have the valve cover removed to look inside before purchase. If deposits/sludge is in the engine, wouldn't a switch to full synthetic like Mobil 1 help to start cleaning it out?

Unless previous owners paid extra, you can bet your paycheck that a cheap bulk oil is used. What do the records say? 10k mile oil changes? That’s your culprit.

M1 FS 0w40 is about the only one in the Mobil lineup that has the correct chemistry to clean, and even it will take several oil changes. There are some other quicker routes to cleaning, but it’s not available with any WM shelf oils.

 

[dishdude]

Agreed this is normal. That baffle doesn't have oil flowing over it when the engine is running.

 

[michaelluscher]

Normal on MZ V6s

Mine is pretty carboned up, but the valvetrain under the covers is immaculate

 

[Brian123]

Correction... 2005 Highlander.... I should add the valve cover gasket is leaking a bit. I sort of doubt cheap oil was used. It was serviced at Toyota dealers a lot and owner says hybrid oil used. There will be no way to have the valve cover removed to look inside before purchase. If deposits/sludge is in the engine, wouldn't a switch to full synthetic like Mobil 1 help to start cleaning it out?

NO

 

[NissanMaxima]

Unless previous owners paid extra, you can bet your paycheck that a cheap bulk oil is used. What do the records say? 10k mile oil changes? That’s your culprit.

M1 FS 0w40 is about the only one in the Mobil lineup that has the correct chemistry to clean, and even it will take several oil changes. There are some other quicker routes to cleaning, but it’s not available with any WM shelf oils.

Looks like about every 5 k on carfax. Oil and filter changes mostly at Toyota. Some at independents, or Brakes Plus, Big O, etc.

 

[NissanMaxima]

They are amenable to having an inspection. Can I trust a Toyota technician's judgment on this without an invasive examination? Asking price is very attractive. Other than a small fender bender, car is in very good shape. Interior extra clean and cared for. First owner was lease for 3 years.

 

[Oliveoil2]

Photo please

 

[GSCJR]

It's normal, my 1MZ-FE had a crusty looking baffle with 5k km oil changes, it's a coating, it means nothing regarding it's vital internals. One of the best vehicles I've ever owned, you won't regret it. DO IT!

 

[NissanMaxima]

Photo please

For some reason, this photo makes it look worse than it was. It wasn't fully coated across the entire surface like this. Maybe the lighting. I pulled the dipstick and oil was super clean. Again carfax shows oil and filter changes about every 5k.

 

[michaelluscher]

This was mine after 200k
If it's had the changes documented, expect light varnish but no sludge
If you buy it, expect that it'll probably need valve cover gaskets at this age and mileage
And I'd put a new PCV valve

The "OLM" MAINT REQD light is just a dummy 5,000 mile counter

If the rest of it checks out, I'd buy it

 

[Kira]

The slotted grate in the filler neck of every B5224S (5 cyl. Volvo engine) I've seen was chunked up with black stuff.
Heat rises after shutdown and cooks the oil that's there.
Ugly but normal.

 

[kschachn]

Your picture is a normal baffle. Toyota uses a dark textured coating of some sort, it looks the same as on my old 1MZ-FE.

This causes all sorts of consternation and there have been several threads about it here on Bitog as well as other boards. What you have is not from the oil. It was there from the factory.

 

[NissanMaxima]

Your picture is a normal baffle. Toyota uses a dark textured coating of some sort, it looks the same as on my old 1MZ-FE.

This causes all sorts of consternation and there have been several threads about it here on Bitog as well as other boards. What you have is not from the oil. It was there from the factory.

Thanks!
And now I'm "baffled". My recollection is it was an actual carbon coating on an unfinished, metal baffle Some bare metal was still visible to the sides, and where it existed, I could dislodge some of it to reveal metal beneath. Unless... that was the black coating eroding??