Please Help! Milky Oil!

I have a 1975 Ford F150. The motor is rebuilt 390 with new rings, bearings, and gaskets. I really have a problem with the oil looking kind of milky. I have put on about 500 miles after rebuild and changed the oil twice (100 miles after and about 450 miles after.) I dont drive it very far, to school and back, and to my friends house five miles out of town. I haven’t seen any loss of coolant or oil, but when I pull the dipstick this white stuff is all the way up the dipstick and a little in the oil. I also pull the oil fill cap off, and it is all in there too. I have good oil pressure, and it cools fine. My frieds dad knows a lot about cars and I asked him and he thinks it is just condensation because I just drive it around town and out to their house. My friend is worried that we put the intake on wrong, but wouldn’t have that leaked as soon as we started it? My oil also turns dirty very soon. I know about after 400 miles of driving, the oil turned to a very dark brown. With this black oil and white stuff, it looked just like cappachino. She fires right up, doesnt sputter, it only smokes in the morning when it is cold, I seem to have no loss of power that I can see, there is no oil or antifreeze running out of the glasspack on it, and it doesnt knock. We got the motor running around July and on it was on the road about the middle of August, and the oil looked fine then, it just turned to this as soon as it got cold.

Me, my dad, and my friend put a whole summer of 10 and 12 hour work days in that motor, and I was planning to drive it for a long time.

What do you think?


It’s just condensation - you’re dad is likely right. By driving it short distances, the engine isn’t getting up to operating temperature long enough (if at all) to boil off the oil contaminants. Over time, this water and stuff in the oil will cause havoc with the engine, due to the lack of lubricating properties of water. By continuing to drive this way, you will most definitely toast your engine quickly.

To get rid of the crap, you need to take the truck out for a good half hour or so highway jaunt, where the engine will be up to proper operating temperature for a decent amount of time - this way the crud will boil off.

Also, if your truck has a PCV valve, change that as well. It should be fairly cheap, and wouldn’t hurt to change it anyway.

You also probably have cylinder “blowby”, where your rings do not seal perfectly and combution gasses get intop the crankcase. First, as pointed out, give the truck some exercise to blow off the water in the oil. Then keep an eye on it; if the mily stuff reappears on the dipstick, you defintely have blowby, which indcates new rings.

What kind of oil are you using to break in the motor? Have you done any post-rebuild compression/leak down checks to gauge the progress of ring break-in?

Another good way to tell if you’re burning anti-freeze is to check the spark plugs. If they are bright white and appear sandblasted, you may be burning coolant.

Sorry… but if the oil is milky you have coolant in the crankcase. This is NOT a condensation problem with so little mileage after the rebuild. I’ll bet the intake gasket is not lined up properly and it’s leaking internally.

Stop driving it right away and fix this problem before you destroy the engine.

IF the gasket has breached and coolant is mixing with the oil and you drove it (How many miles after you noticed the milky oil?) for too long, there MAY be damage done to the crankshaft bearings by now.

If it’s not missing any coolant, where is the coolant in the oil coming from? And why was it apparently sealed just fine for the first several months of operation?

I agree with your father. Crankcase blowby will condense in the colder parts of the engine which are the valve covers, dipstick, timing chain cover, and lifter valley/intake manifold. Make sure you have a working thermostat and use the highest temperature one available. Change to a cooler thermosat in the summer. Since the engine is still getting broken in you are getting more blowby of the rings than you will have once the rings are seated.

As others have said make sure the PVC system including the fresh air input are in working order and connected.

You have to run the engine long enough under enough throttle to get enough hot gases up to the valve covers to evaporate the condensation. You can probably get a handle on the correct valve cover temperature by dripping some water on the outside and see if it evaporates quickly.

You are probably going to have this problem all cold season until the rings seat, then you should be okey. But keep changing the oil and maybe clean out the valve covers until you get control on the condenstation.

You are taking the word of the O.P. that it isn’t missing coolant. Plus how much coolant do you think it takes to turn the oil milky? Not much.

For the oil to turn milky/brown that quickly indicates a coolant leak NOT a condensation problem.

He also states that he changed the oil after a 100 miles then 450 miles and the oil turned brown shortly after. That is not a condensation problem. A condensation problem takes time to show up like this. Alot longer than 100 miles or 450 miles.

The O/P/ needs to pressure test the cooling system for leaks, I’ll bet it isn’t holding pressure.

Condensation will show up on the dipstick above the level of the oil, under the oil fill cap, but the oil itself should NOT look like a milkshake unless the problem has been occurring for a long, long time. So I think willey is correct, unfortunately.

I think Willey is correct on all counts.

On second thought, I have to agree with Willey as well. I hadn’t considered the low mileage. However, one thought - the OP stated he just drove around town, so it could take a little while to get 450 miles on the truck. How long does it take in city traffic to see condensation in the oil?

390bigblock-power… If you believe it’s a condensation problem then here’s what you need to do. Install a new t-stat, change the oil, and closely monitor the condition of the oil. Inspect it every day. I want to know exactly when the oil becomes milky again.

Here’s what I belive is happening. The intake gasket moved when you installed the intake manifold, just a small amount by the coolant passage in the corner of the intake. It is leaking internally, down the valley where the lifters and cam are located. That is why there isn’t any coolant present externally.

I changed the oil for the second time around the beginning of November because I noticed it was black and milkey. The oil started to look milky around the middle of December. It isnt black yet but it doesnt look very good either. There was another thing I forgot to mention, the white stuff also blows out of the PCV valve. The old motor I had in there, the head gasket went out, and it didnt look like this. The oil was green when that happened.

There would have to be a lot of condensation in the crankcase to create the milky oil. There is no doubt that there is coolant in the crankcase. Check the coolant usage it is probably pretty high.

I am using Super Tech 10-W-40 oil. I havent done any checks on the motor because I dont have any tools to do that.

Isn’t that synthetic oil???
Some modern engines can be broken in and run on synthetics due to their tight manufacturing tolerances, machining methods and the materials used. I would never break in a vintage motor with anything but conventional oil. You’ll likely get some dissenting opinions in this regard. But in my experience, synthetics may not allow the rings to properly seat. This is a critical period in the engine break in and it is possible to get past a point where the mating can no longer happen correctly.

If it is synthetic, I’d change it immediately. Once the conventional oil has had a chance to circulate well through the motor, take it out for some stiff romps. I’m not saying to excessively load, rev or shock the motor from a standing start, but some good hard romps as you’re rolling along. Hard to explain but hopefully you get the idea. You want to get the combustion pressures up there to force the rings to seat. This can make all the difference in motors having trouble with ring seating.

And by all means, keep a critical eye on the coolant level in the rad. Don’t trust the expansion tank if you have one, check the radiator to be absolutely sure. Check it stone cold each day to make sure it’s not dropping and check your oil often. Antifreeze will kill your bearings quickly.

Twin Turbo is right! A conventional old style engine with larger clearances should have standard mineral oil for the first 2 oil changes, so that the rings will seat properly. I would drain the synthetic immediately. The blowby which results in milky stuff on the dipstick is probably due to improper sealing. My new Toyota is not supposed to take synthetic oil for the first 3 oil changes, according to my dealer. They are foregoing a significant profit opportunity by recommending regular oil!

Thanks for you answer Twin Turbo and Docnick. The oil I am using is just standard mineral oil. I know my friend was mad at me because he said I should haved used synthetic oil too. Then he said that I should have used high milage oil, I didnt know why because the motor had 0 miles on it. The oil I am using is just the cheapy oil from walmart, but I have heard from many mechanics around my area that oil is just oil, (brands dont matter.) I dont know if that is true or not, but Ive used it in my truck, my dad uses it in his cars, and it doesnt seem to change anything.

I was praying that the intake wasnt messed up when we put it on, and it doesnt seem to be. The level in the radiator was the same level as what it was when I filled it up for the first time.
I know I need to drive it more, and I am going to. I am going to do what you said and take it out on a trip and romp it a few times.