Question about condensation or gunk on oil cap

S

Shel_B

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Aug 7, 2020
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The oil was changed on the ol' Camry today after about 6 months of short trip driving. Most trips have been less than six miles, usually with a stop and engine off mid-point. I've seen pics of other cars driven similarly, and quite a few have a mayonnaise-like buildup on the oil cap. That buildup has been described as a result of condensation mixing with oil/oil fumes. The Camry has no such buildup, and the underside of the cap looks almost like new. I'm not complaining.

I'm curious why there's no buildup in my situation. I have some thoughts but would like to know what others think.
 
Maybe your Camry is too old to produce Mayo. :D

It is the season, if you don't have it now you probably won't. Looking down the fill can you see the cams and valvetrain. If they are near the cap it is probably being splashed clean.
 
Shel_B said:
I'm curious why there's no buildup in my situation. I have some thoughts but would like to know what others think.
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Were they other Camrys you were seeing, or just other cars in general?

I wouldn't worry about it. It might even be as simple as something like how much humidity is in the air. The other guy across the country gets condensation, while you don't.

My Cobalt gets some liquid - a bit of oily water, really, not milkshake - on the bottom of the oil fill cap. I attribute it to a) the cap is located up high on the top of a surprisingly tall plastic "chimney", and b) it is further isolated from much hot air by an additional baffle under the valve cover. In cold weather, I don't think the oil cap even gets warm. I don't worry about it.
 
PF52 said:
Were they other Camrys you were seeing, or just other cars in general?

I wouldn't worry about it. It might even be as simple as something like how much humidity is in the air. The other guy across the country gets condensation, while you don't.

My Cobalt gets some liquid - a bit of oily water, really, not milkshake - on the bottom of the oil fill cap. I attribute it to a) the cap is located up high on the top of a surprisingly tall plastic "chimney", and b) it is further isolated from much hot air by an additional baffle under the valve cover. In cold weather, I don't think the oil cap even gets warm. I don't worry about it.
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Other vehicles in general, perhaps even a few with the same engine as my car.

I'm not worried. Not even concerned. Just curious about possible reasons.
 
The reason is that your oil cap screws in very close to where all the action is happening, maybe a half inch above a spinning camshaft. There is a baffle right there but the fact of the matter is, its very close to the spinny things of the engine, probably receives a lot of air flow and generally I have found toyotas usually have pretty toasty valve covers.

Where you'll see condensation is where the vapors are able to cool off in stagnant air.
 
Shel_B said:
The oil was changed on the ol' Camry today after about 6 months of short trip driving. Most trips have been less than six miles, usually with a stop and engine off mid-point. I've seen pics of other cars driven similarly, and quite a few have a mayonnaise-like buildup on the oil cap. That buildup has been described as a result of condensation mixing with oil/oil fumes. The Camry has no such buildup, and the underside of the cap looks almost like new. I'm not complaining.

I'm curious why there's no buildup in my situation. I have some thoughts but would like to know what others think.
Click to expand...
9 times out of 10, mayo under the fill cap is some degree of coolant contamination. People do not like to hear that.
 
Not uncommon to see that during cold weather months. I’ve lived in Missouri and Colorado all of my life and every car I’ve owned does that during the winter. Never seen it during the summer. I think where you are in CA it doesn’t get cold enough to get it.
 
I had that situation occur before. All you can do is make sure the PCV is functioning and the breather is clear. Otherwise utilizing some longer trips will burn off built up moisture.
 
Buckwheat said:
The regular short trips are killing the engine regardless
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This ^^^^^^^^

The worst thing for a vehicle, is continuous, short trip driving in freezing cold, Winter climates. The oil never gets up to operating temperature, and it will have subsequent condensation build up...... Often referred to as, "Mayonnaise".

The cure for this couldn't be any simpler or easier. Once or twice a week take the vehicle out for a ride on the highway for 20 or 30 minutes. The oil will then get up to operating temperature, (over 200F). And in the process it will evaporate any moisture that has built up in both the engine, oil, and exhaust system.

It will also allow the catalytic converter to heat up to its operating temperature, and burn off any carbon and contaminates. Down the road your vehicle will thank you for it.
 
I put new valve covers on recently. The OEMs had 250k on them. Whatever is making it up into that filler tube and the cap is also on every working part underneath. If you think it's a death sentence then it's prob time to get that battery mobile you've secretly always wanted.
 
Shel_B said:
Other vehicles in general, perhaps even a few with the same engine as my car.

I'm not worried. Not even concerned. Just curious about possible reasons.
Click to expand...
Drive it in MN and I bet you will have some. It is your climate.
 
Most Ford Tritons seem particularly bad about this, at least in cold climates. Doesn't necessarily mean you're getting coolant in the crankcase -- some engines just seem worse about condensation. I'm sure theories could be formed as to why if the overall design was scrutinized.
 
D60 said:
Most Ford Tritons seem particularly bad about this, at least in cold climates. Doesn't necessarily mean you're getting coolant in the crankcase -- some engines just seem worse about condensation. I'm sure theories could be formed as to why if the overall design was scrutinized.
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My 98 5.4 here, only happens in the harshest of winters for me. First time it happened I thought for sure I had a head gasket issue but that wasn't the case, 20 years later its still not the case.
 
billt460 said:
This ^^^^^^^^

The worst thing for a vehicle, is continuous, short trip driving in freezing cold, Winter climates. The oil never gets up to operating temperature, and it will have subsequent condensation build up...... Often referred to as, "Mayonnaise".

The cure for this couldn't be any simpler or easier. Once or twice a week take the vehicle out for a ride on the highway for 20 or 30 minutes. The oil will then get up to operating temperature, (over 200F). And in the process it will evaporate any moisture that has built up in both the engine, oil, and exhaust system.

It will also allow the catalytic converter to heat up to its operating temperature, and burn off any carbon and contaminates. Down the road your vehicle will thank you for it.
Click to expand...
I agree with all of the above but I do non of it. 18 years of short tripping in the north east still original exhaust, converter, antifreeze actually engine never opened up for a repair. I'm lucky so far but I do add my fair share of oil between changes
 
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