Since you changed the oil why don’t you monitor it and purchase an oil analysis kit($24 for WIX on Amazon). After 500-1000 miles send a sample of the oil to the laboratory and if coolant is present you’ll know. It won’t isolate the issue but it will determine if coolant is present and the percent of coolant. As an aside my oil in the pan looked similar after putting Amsoil engine flush in to remove contamination from conventional oil. A “froth” of varnish removed is how I would describe it.

 

I see similar symptoms at my local shops in winter days. The engine oil partially colored like a milk coffee and a filler cap is something like this below.
This happens among cars driven by housewives who don't drive long distance in cold winter days. They just drive to local grocery stores and others just for shopping. The moisture trapped in the engine causes the problem. Sometimes a failed PCV valve causes the problem too.


Do you drive short distance often and also is the climate icy cold?

 

I would change the oil again, drain everything out thoroughly, clean the cap and monitor it closely. For the small investment, you can observe further. The cold climate is a major factor in your case. If you were noticing any of this during the warm climates I'd lean more towards a definitive problem. If you want to do an oil analysis after, that's another option. Keep us posted and good luck to you. It's certainly worth a shot before throwing in the towel.

 

As mentioned above looks like it could be condensation from oil and Pcv system. If car is acting normal and has not overheated I would do a drain and fill and monitor it after a few drive cycles. May be nothing. These motors are tanks that are pretty hard to grenade.

 

I'm a bit late to the party on this, but I have first hand experience with this in another car I used to own - a 2000 Mercedes E320. I had a frothy white mess under the oil cap. After a bunch of research, came to find out that this was considered normal. Something with internal engine venting, and only happened during the winter months. Never had an issue with that engine.

I see you're in MN, so it's no doubt cold there. Might be a non issue, but my experience was with a different car.

Have you topped up the coolant to see how long it takes for the level to go down? Any excessive white smoke from the exhaust, beyond the normal winter vapor? If you have a blown head gasket, it will be obvious, and the exhaust will have a distinctly sweet smell.

 

Again, I would not worry about it. I'll say it again, when I had my car day 2 and there was zero coolant in the reservoir and none to be seen in the radiator, I used common sense, this vehicle has blown head gaskets and I just got ripped off for $14k cash money ouch (although by NYS law I had a 30 day/1k miles powertrain warranty so I figured I'm going to have to use it). That was almost 39 months ago and there never was an issue at all with the cooling system. So just think this car can run with an improper amount of coolant and the engine is not harmed (never got hot temp gauge same low coolant/proper coolant)

 

If the OP has more than one symptom, it can also help in diagnosis. The milky cap is certainly not the end all. However, if there is a sweet smell in the exhaust upon cold start ups, noticeable depletion of coolant, milky oil on oil dipstick, and any discoloration in the oil upon the next oil change, there might be issues. The milky cap alone is no reason for alarm in the cold weather.

 

Sorry for the late response. I do notice a sweet smell in the cabin on cold starts. When I accelerate hard I also notice more smoke out the tailpipe than usuall. Also, the dipstick does have some froth on it...

 

Sorry to read there may be an issue. Don't know if you may wish to look at this thread: https://www.clublexus.com/forums/ls-...ad-gasket.html

 

Sorry to hear this. You may nearing a major decision on how to proceed. If indeed your head gasket needs replacement do you want to absorb the exorbitant expense on such an old car? Also there is always possibility of the “collateral damage “ that might accompany the disassembly and reinstallation Good luck with whatever decision you make.
PS. The sweet smell inside the car might be a leaking heater core but you still have the excessive smoke from exhaust and the froth on the dipstick. Is the exhaust color very white with a sweet smell? Are you losing coolant?

 

I check the resevoir about once every month or two and I need to refill completely about once every month and a half. I've thought of the heater core as an issue, but doesn't seem likely to me. Actually had that issue on an older 1994 LS400.

Anyways, I think it may be time to retire the car. 162K on the car and it needs suspension work all around. I'm just confused because as I'm aware the car has never overheated and does not overheat while driving... Then again these cars can take a major beating, so I guess I'm not sure.

 

The reservoir can be over filled and subsequently leak. Pull the radiator cap when the vehicle is cold, top it off and run until the thermostat opens. Shut it down and then top off the radiator but go no more than an inch above the “low mark” on the reservoir when you fill it.

if it still uses antifreeze at the same rate and a cooling system pressure check doesn’t indicate an internal coolant leak then sample the oil for coolant. Before retirement please sample the oil as it may not be a head gasket.