I was changing the oil on the family truckster - a 2002 Chevy Tahoe when something happened that I have never seen before.
I drained the oil, changed the filter and refilled with M1 5w30 - OK so good. Fire the car off let the engine run, check for leaks & cut her off. My 5.3 V8 takes like 5.75 qts to get to the full dipstick line so I elected to use some old M1 0w40 from about 3 years ago: a genuine SL/GF3 oil of yore.
I had opened the oil and used it in the lawnmower probably 3 years ago and sealed it back up and, uh kinda forgot about it. It sat on the garage shelf for those three years. Fast forward to today.
Opened that bad boy up and began pouring it into the engine and it looked really dark. Then, I could smell a hypoid like smell. I ceased operations immediatly and checked this stuff out. I poured what was left in the bottle into a clean pan and it was some kinda F'dU!! The bottom of the bottle had a black slime, just a thin layer mind you but none the less really bad looking stuff.
This opened up (but resealed) bottle had endured Houston's humidity and the years of temperature changes while sitting on the garage shelf but quite frankly I was amazed at the transformation.
I dumped the whole crankcase of fresh M1 and filter (boy does that hurt)and ran a gallon of Mobil's conventional oil through the engine straight into a catch can to flush the engine of that sh!t. New oil and filter and she is good to go but I learned a lesson here: If it's been opened once you better use it up pretty quick or throw it away.
Anybody care to speculate what happened? I'll start with this - I think this bottle of M1 was near 100% PAO and over the years absorbed moisture and was heat / cold cycled while never being disturbed, thus the add pack fall out. Anybody else got any ideas? Cheers DV
I drained the oil, changed the filter and refilled with M1 5w30 - OK so good. Fire the car off let the engine run, check for leaks & cut her off. My 5.3 V8 takes like 5.75 qts to get to the full dipstick line so I elected to use some old M1 0w40 from about 3 years ago: a genuine SL/GF3 oil of yore.
I had opened the oil and used it in the lawnmower probably 3 years ago and sealed it back up and, uh kinda forgot about it. It sat on the garage shelf for those three years. Fast forward to today.
Opened that bad boy up and began pouring it into the engine and it looked really dark. Then, I could smell a hypoid like smell. I ceased operations immediatly and checked this stuff out. I poured what was left in the bottle into a clean pan and it was some kinda F'dU!! The bottom of the bottle had a black slime, just a thin layer mind you but none the less really bad looking stuff.
This opened up (but resealed) bottle had endured Houston's humidity and the years of temperature changes while sitting on the garage shelf but quite frankly I was amazed at the transformation.
I dumped the whole crankcase of fresh M1 and filter (boy does that hurt)and ran a gallon of Mobil's conventional oil through the engine straight into a catch can to flush the engine of that sh!t. New oil and filter and she is good to go but I learned a lesson here: If it's been opened once you better use it up pretty quick or throw it away.
Anybody care to speculate what happened? I'll start with this - I think this bottle of M1 was near 100% PAO and over the years absorbed moisture and was heat / cold cycled while never being disturbed, thus the add pack fall out. Anybody else got any ideas? Cheers DV
