oil mixed in my coolent
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Tannmann36
- SE Member

- Posts: 11
- Joined: Sun Feb 27, 2022 11:52 pm
- Year and Trim: 2001 SE
oil mixed in my coolent
So first of, it feels like I make a new post every day but I'm kinda dumb when it comes to engines. So I said about coolant leaking and the coolent looks almost muddy and dirty. Turns out that it's oil in the coolent. I honestly don't know what's causing this but I definitely believe now that it might be a head gasket. If there's anything else it could be please let me know and thanks.

Belvedere: 2001 Pontiac Bonneville SE
Cleared corners - tinted fogs - bone stock
- 95naSTA
- Certified Bonneville Nut

- Posts: 7087
- Joined: Wed May 21, 2008 11:47 pm
- Year and Trim: 95 SLE
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Re: oil mixed in my coolent
LIM gaskets as mentioned in your other coolant thread. Don't run the engine since coolant is mixing with oil and coolant doesn't lubricate bearings.
These cars don't have head gasket failures in n/a format.
These cars don't have head gasket failures in n/a format.

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers
Info on dropping a 92-99: Here.
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Interceptor_843
- SE Member

- Posts: 15
- Joined: Sun Jun 18, 2023 3:19 pm
- Year and Trim: 2004 Pontiac Bonneville SLE.Top Swapped.
Re: oil mixed in my coolent
What sort of coolant have you been running/ is in the motor? Did you check your oil level and what it looks like? Is your coolant a thick milkshake or is it just dark and brown.
If its straight liquid, its usually cause of stupid dexicol and someone running water instead of coolant. Your more than likely, to remove that color, is to fully flush your cooling system, prob replace your radiator, and i would check your water pump as well.
While your at it, replace your coolant elbows (Check lower intake manifold, belt side) if they are plastic. If they are black, replace them with aluminum ones as soon as possible. There is two, requires removing the alternator to get to the second one.
Lastly, dexicool is, from my experence (I had my elbows blow out on me and previous owner attempted to use stop leak to hide the issue), the worse coolant and you need to completely flush the stuff out your cooling system. Im having to replace my radiator due to buildups and such.
Again, this is my experence. And make sure you get the green coolant, thats the good stuff.
If its straight liquid, its usually cause of stupid dexicol and someone running water instead of coolant. Your more than likely, to remove that color, is to fully flush your cooling system, prob replace your radiator, and i would check your water pump as well.
While your at it, replace your coolant elbows (Check lower intake manifold, belt side) if they are plastic. If they are black, replace them with aluminum ones as soon as possible. There is two, requires removing the alternator to get to the second one.
Lastly, dexicool is, from my experence (I had my elbows blow out on me and previous owner attempted to use stop leak to hide the issue), the worse coolant and you need to completely flush the stuff out your cooling system. Im having to replace my radiator due to buildups and such.
Again, this is my experence. And make sure you get the green coolant, thats the good stuff.
______________________

2004 Pontiac Bonneville SLE
Top Swapped, Gen5, ZZP front power log, custom rear power log and downpipe, 3.4 pulley, 1.95 rockers, ZZP lifters, big boy trans cooler, 180 themo, Complete AC delete, custom intake, local dyno tune, small other goodies. GXP dash swap, Aftermarket head unit, twin 12 inch kickers, PS2 and Small TV for rear seats.
Top speed is my goal, 150 MPH so far.

2004 Pontiac Bonneville SLE
Top Swapped, Gen5, ZZP front power log, custom rear power log and downpipe, 3.4 pulley, 1.95 rockers, ZZP lifters, big boy trans cooler, 180 themo, Complete AC delete, custom intake, local dyno tune, small other goodies. GXP dash swap, Aftermarket head unit, twin 12 inch kickers, PS2 and Small TV for rear seats.
Top speed is my goal, 150 MPH so far.
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Tannmann36
- SE Member

- Posts: 11
- Joined: Sun Feb 27, 2022 11:52 pm
- Year and Trim: 2001 SE
Re: oil mixed in my coolent
So this is what the coolant looks like in three spotsInterceptor_843 wrote:What sort of coolant have you been running/ is in the motor? Did you check your oil level and what it looks like? Is your coolant a thick milkshake or is it just dark and brown.
If its straight liquid, its usually cause of stupid dexicol and someone running water instead of coolant. Your more than likely, to remove that color, is to fully flush your cooling system, prob replace your radiator, and i would check your water pump as well.
While your at it, replace your coolant elbows (Check lower intake manifold, belt side) if they are plastic. If they are black, replace them with aluminum ones as soon as possible. There is two, requires removing the alternator to get to the second one.
Lastly, dexicool is, from my experence (I had my elbows blow out on me and previous owner attempted to use stop leak to hide the issue), the worse coolant and you need to completely flush the stuff out your cooling system. Im having to replace my radiator due to buildups and such.
Again, this is my experence. And make sure you get the green coolant, thats the good stuff.

This is what it looks like in the coolant reservoir
This is the coolant in the radiator

And this is coolant i collected from the bleeder valve which to me looks like brand new coolant. im not saying coolant still isn't mixing with the oil but its just weird how it looks different in different areas in the car. and oil level always goes down, it has since i got the thing the seals are bad and it does leak oil. the reason im asking all of these questions in the first place it so see what could actually be wrong with it before i go and spend 1 or 2 grand on repairs for something that isn't even the problem. Anyway thanks to everyone for the help and i will diffidently look into having someone check the LIM and UIM gaskets to start and unfortunately i cant just stop driving the car its the only thing i have to drive and i drive it like less than 20 miles a day for work.

Belvedere: 2001 Pontiac Bonneville SE
Cleared corners - tinted fogs - bone stock
- 95naSTA
- Certified Bonneville Nut

- Posts: 7087
- Joined: Wed May 21, 2008 11:47 pm
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Re: oil mixed in my coolent
I don't see oil in the coolant.
Look at your oil dip stick. If it looks like a chocolate milk shake instead of oil, you have coolant in your oil and you will destroy your engine driving it.
Look at your oil dip stick. If it looks like a chocolate milk shake instead of oil, you have coolant in your oil and you will destroy your engine driving it.

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers
Info on dropping a 92-99: Here.
-
Tannmann36
- SE Member

- Posts: 11
- Joined: Sun Feb 27, 2022 11:52 pm
- Year and Trim: 2001 SE
Re: oil mixed in my coolent
Nope looks fine just checked it today.95naSTA wrote:I don't see oil in the coolant.
Look at your oil dip stick. If it looks like a chocolate milk shake instead of oil, you have coolant in your oil and you will destroy your engine driving it.

Belvedere: 2001 Pontiac Bonneville SE
Cleared corners - tinted fogs - bone stock
- nos4blood70
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- Location: Chicago, IL
Re: oil mixed in my coolent
Either upper intake manifold or lower intake gaskets. Look between the head and the lower intake. If you see a silver gasket, I'd be more inclined to say you have UIM failure. If you see a black gasket, it could be one or both.
You should replace the LIM gaskets, and the UIM. Do a few oil changes with cheap oil to flush her out.
I had this failure at ~60k miles.
You should replace the LIM gaskets, and the UIM. Do a few oil changes with cheap oil to flush her out.
I had this failure at ~60k miles.
- luke_dubs
- GXP Member

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- Year and Trim: 2013 Regal GS
- Location: OH
Re: oil mixed in my coolent
Replace both the upper and lower intake manifold gaskets, as stated above. That should prevent this from happening again; thankfully you caught it before any damage was done to the engine.

'02 Pontiac Bonneville SE 108,539 miles, N/A, SSEi exhaust system, boat roller mount. Gone, but not forgotten.
'13 Buick Regal GS 122k miles, 270 hp, 295 lb/ft, ZZP intake.
(yes, there is a story behind my avatar.)
Re: oil mixed in my coolent
Yep I just had the exact issue on my 2004. It just turned 40000 but I thought it might go longer before replacing the lower intake. When I opened the motor, one of the coolant ports had alot of dex-slime. Found the plastic gasket failed on that side and the others were following. Dug out as much dex-slime as I could and replaced the intake gasket with the metal GM.
Go with GM not the Felpro gasket. Felpro are probably are ok but looking at them side by side Gm/delco has the superior quality by alot.
One other thing to note is the thicknesss of the new GM metal gasket will move the up the intake and slightly change the alignment of the alternator brace. Make sure you position the brace before you torque down the intake or you might cross-thread the brace bolt trying to get it started later. I had to use a cheap grade bolt to get one location started, couldnt get both stock bolts to start. I could have also ground down the brace a bit.
Clean out the reservoir with Brake Kleen and flush the radiator/block.
IMO Dexcool is ok. I had it in my other 3800 after the intake gaskets were replaced. 350,000 miles no problems. If you switch to green, plan to flush it at least every other year.
So far the coolant looks good, but plan to flush the radiator and reservoir once more before winter.
I had a few pics of the gasket and port but don't remember how to insert here, do we still need a photo host? or can I paste somehow?
Go with GM not the Felpro gasket. Felpro are probably are ok but looking at them side by side Gm/delco has the superior quality by alot.
One other thing to note is the thicknesss of the new GM metal gasket will move the up the intake and slightly change the alignment of the alternator brace. Make sure you position the brace before you torque down the intake or you might cross-thread the brace bolt trying to get it started later. I had to use a cheap grade bolt to get one location started, couldnt get both stock bolts to start. I could have also ground down the brace a bit.
Clean out the reservoir with Brake Kleen and flush the radiator/block.
IMO Dexcool is ok. I had it in my other 3800 after the intake gaskets were replaced. 350,000 miles no problems. If you switch to green, plan to flush it at least every other year.
So far the coolant looks good, but plan to flush the radiator and reservoir once more before winter.
I had a few pics of the gasket and port but don't remember how to insert here, do we still need a photo host? or can I paste somehow?


