Green oil

1995 GMC JIMMY
190,000 MILES • 4.3L • V6 • 4WD • AUTOMATIC
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RICKYD1233
  • MEMBER
  • 5 POSTS
I just replaced the timing chain and gears in my wife's vehicle. I drained the oil. It had a strong green tint. It was not foamy like I had a blown head gasket. After the timing chain job she drove it about two weeks and I changed the oil again. It still has that green tint. I change the oil every three months. The has never looked like this before. I do not smell anti-freeze in the oil, but I do not have a great sense of smell. Any ideas what it could?
Aug 1, 2017 at 7:28 AM
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CARADIODOC
  • ✓ASE Certified Mechanic
  • 34,321 POSTS
  • ASE Certified Mechanic
The best suspect is someone added dye to the oil in the past to help in finding the location of a leak. When an engine takes five quarts of oil during a change, it actually holds about seven quarts. Two quarts in the pump and passages never drains out. It could take a dozen oil changes before all the dye is gone.

If my guess is right, the old oil will turn bright yellow if you shine a black light on it. Many auto parts stores have tools to rent or borrow. Stop in there and ask them to briefly shine the light on the bottom of your "oil" cap.
Aug 1, 2017 at 6:32 PM
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