All Big Six Na+ and K+ oil contamination

Relates to all big sixes
I bought a '94 F150 with 160K last summer that that needed a little work. It's got the 4.9 L6.

On second oil change I figured I'd send oil into Blackstone Labs and this is what they said: "This sample shows some coolant contamination, visible at the high potassium and sodium levels." Specifically they're reporting 60 ppm Potassium and 140 ppm Sodium, which I think is a clear red flag. Later on under Antifreeze % they say "POS" which I suppose means positive. Darn it, I hoped the 300 was good for 300K.

Truck runs better than fine: clean start, nice idle, plenty of power, and doesn't need regular coolant top-off. Some of the coolant hoses do weep a bit though.

What do y'all think? Is my engine doomed; do I have a blown head gasket? Should I try to resurface and replace the gasket; or drive till it starts overheating all the time?
 

Sevensecondsuv

Well-known member
Well I'll just give my perspective:

My truck is a '95. I bought it ten years ago from a farmer friend who bought it new. At some point during his ownership, the oil pan rusted through, causing a major leak. Unfortunately he was super busy that year, so he would fill it with used 15w-40 from the tractors, drive it until it got low enough to lose oil pressure, fill it back up, and repeat, for a full year before the oil pan finally got replaced. Meanwhile he was routinely grossing over 20k with the poor thing. He eventually got a new truck, which is when I bought it. I haven't been quite as hard on it, and actually put fresh oil in it once a year, but still work the thing hard - I'll never forget the day I hauled 50 yards (multiple trips) of gravel from the local quarry.

And I've never once done oil analysis or worried about the head gasket!
 

hodaka100

Well-known member
If it aint broke dont fix it. Research what you want with your analysis but most people never get one. I put my 1988 300 through hell and it was the body that quit after 245,000 miles not the engine... Low oil: listen to the lifters tap driving it to the nearest oil store, water pump leaking: drive it 8 miles to autozone with the temp gauge pinned to stall at the red light pulling in. After a minute of cool down it started back up to get in the parking lot and change on the spot. Hydro lock it in a flood: pull the plugs to clear it out and drive out to change the oil a few times to get the milk out. Leave it in the back yard with the hood cracked for two years to find its locked up with 5 gallons of water in the oil pan: Spend an hour breaking it free and its back on the road ( this one did break a piston ring but i didnt know until i tore down the engine after scrapping the truck many years later. Let a friend do do-nuts in a corn field: he didn't watch the temp gauge and it locked up from overheating but 5 minutes later it was back on the road. The 300 is a "bullet proof" engine.
 

THE FRENCHTOWN FLYER

5K+
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My '85 van drank anti-freeze at the rate of a couple of overflow bottles a year. It never smoked (steamed) or ran poorly. Always ran great. It just consumed coolant. I kept the reservoir filled and it never balked.
 

sixtseventwo4d

Well-known member
Drive it until a second oil change is needed. Have another analysis done and see if gets worse. Use that as part of your deciding factor. The appreciable point is that it's easy enough to replace the head gasket if you decide to. One thing I would not do is use one of those "pour in" remedies. Until then, drive it like you stole it!
 

Frank

Well-known member
Supporter 2021
I bought a '94 F150 with 160K last summer that that needed a little work. It's got the 4.9 L6.

On second oil change I figured I'd send oil into Blackstone Labs and this is what they said: "This sample shows some coolant contamination, visible at the high potassium and sodium levels." Specifically they're reporting 60 ppm Potassium and 140 ppm Sodium, which I think is a clear red flag. Later on under Antifreeze % they say "POS" which I suppose means positive. Darn it, I hoped the 300 was good for 300K.

Truck runs better than fine: clean start, nice idle, plenty of power, and doesn't need regular coolant top-off. Some of the coolant hoses do weep a bit though.

What do y'all think? Is my engine doomed; do I have a blown head gasket? Should I try to resurface and replace the gasket; or drive till it starts overheating all the time?
Keep the oil changed properly, and just keep driving as you always do. As Hitman said, and it's my longstanding motto too: If it ain't broke, don't fix it."
Diesel engines in most applications of service run incredible hours, often at full or near full load. A truck engine with 900,000 miles (for example), it is considered "normal" to see small compression bubbles emitting from the head gasket, and for small quantities of coolant to be in the oil or passing thru the cylinders from cylinder liner, oil cooler or gasket age. I strongly recommend you make no repairs at this time.
 
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