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Discussion Starter · #1 ·
While I was changing my oil I notices there was foamy oil in the oil cap. This is very concerning because it looks like an indicator of foaming oil in the engine. I keep the oil half way up the dipstick when I check it first thing in the morning. Anyone else observe this?
 

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If you don't have smoke coming out your exhaust (I'm not referring to standard exhaust condensation which evaporates quickly), then it's just condensation in the oil system which is a common occurrence on all types of vehicles.
 
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2018 Madreperla White Coupe
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Hi,
Foam in oil can be caused by several factors. In order of likelihood based on the info you told us:
  1. Water/moisture. You said you checked this in the morning (temperature variation overnight) and the car hasn’t done it’s standard length trips during 2020 - shorter trips where the engine doesn’t get up to temperature for long are considered severe duty. This doesn’t allow the engine to get up to temp and burn off all the moisture. I suggest taking a longer drive and then rechecking for the same problem, if still present...
  2. Additives. Either you added an additive or the defoamant additive has started to be used up due to the additional moisture over the last year from the first item above. Consider how many miles are on this current oil. You are filling up the dipstick halfway, which is a great practice (kudos!) so this gives you the opportunity to top off with some fresh oil and refresh the additive package a little. No need to top off if you’re going with a full oil change soon.
  3. Other contamination. Not sure how often you’re checking for this issue but opening the oil cap invites airborne contaminants to get in the engine. This is likely a non-issue and your oil filter would trap the particles. I would focus on items 1 then 2.

Good luck and let us know how it goes!
- John
 

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Hopefully it's just the short commute I have and not driving it long distance due to COVID.

This article helped.

If you drove short trips for the past 10,000 miles commuting to you office and doing endless short trip after short trip , MAYBE there'd be some foam... but I doubt it.

Please offer more details on your car, mileage, tunes, mods, use and provide a photo, because I am in the "blown head gasket' crowd, and a blown head gasket, local or broad overheating which caused it or it caused can ruin an all aluminum engine.

Milkshake oil: seriously bad news.

When you have a condition that could be nothing or could be serious... welp, you need to investigate the serious side if you're only guessing it's under the 'nothng' side of things. You're guessing.
 

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If you drove short trips for the past 10,000 miles commuting to you office and doing endless short trip after short trip , MAYBE there'd be some foam... but I doubt it.

Please offer more details on your car, mileage, tunes, mods, use and provide a photo, because I am in the "blown head gasket' crowd, and a blown head gasket, local or broad overheating which caused it or it caused can ruin an all aluminum engine.

Milkshake oil: seriously bad news.

When you have a condition that could be nothing or could be serious... welp, you need to investigate the serious side if you're only guessing it's under the 'nothng' side of things. You're guessing.
A few basics. He should check the condition of the coolant too. There’ll be a telltale sign in there if it’s a head gasket issue.
 

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Discussion Starter · #7 ·
Thanks for the comments everyone. There are no other indicators of a problem on my 2017 coupe with 35k miles. Coolant is clean, no smoke, and hold temperature. Over the past 3 months I have not driven 4 miles to work and back and the temp has dropped nto the low 30s here. I just filled with new oil so I'll periodically check the cap and look down the filler hole to make sure.
 

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Thanks for the comments everyone. There are no other indicators of a problem on my 2017 coupe with 35k miles. Coolant is clean, no smoke, and hold temperature. Over the past 3 months I have not driven 4 miles to work and back and the temp has dropped nto the low 30s here. I just filled with new oil so I'll periodically check the cap and look down the filler hole to make sure.
An occasional hard run into the hills will hopefully be all that’s needed. Let us know how it goes.
 

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In certain areas of the world, the climate just makes this a worse problem than other areas (some people will never see this). Just keep the oil cap clean when you see the condensation has turned into milk again, and keep up on your normal oil maintenance.
 

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In certain areas of the world, the climate just makes this a worse problem than other areas (some people will never see this). Just keep the oil cap clean when you see the condensation has turned into milk again, and keep up on your normal oil maintenance.
Years ago I changed oil brands in my Sud from BP Corse+ to Valvoline, probably due to unavailability at the time. Can’t remember. I got lots of foaming and changed back as soon as I could. No foaming has occurred since....except now we can’t get Corse + any more so have gone with Penrite. No foaming.
What oil are you running at the moment; Pennzoil, Selenia or some other brand? Just putting it out there.
 

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An occasional hard run into the hills will hopefully be all that’s needed. Let us know how it goes.
I agree. I had an RX-8 for a little while and that is a common problem if you are only driving short trips. But on the RX-8 it’s disgustingly bad. Like when you pull the dip stick out it’s just like covered...well you get the point.
 
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