Originally posted by ScottK: I'm curious, for those who run extended drain intervals with any oil (say over 5k miles) - what does your new oil look like say 3 days or so after the oil change? Does it look exactly like it came out of the bottle or does it darken up immediately?
My main concern with extending drain intervals is that even if the lubricating properties of the oil are fine that it may saturate with "gunk" and start letting conaminants fall out of solution and form sludge deposits. Quick darkening of new oil is an indicator that the old oil could no longer hold all the crap in solution, leaving the new oil to pick it all up. I know that regular 3000 mile changes with run of the mill mobil leaves my oil looking brand new for weeks after the oil change.
ANY oil, synth or dino, will darken somewhat after the first few (200-1000) miles in-service. It's normal ... And not a primary concern, assuming the old oil was completely drained and a new filter is in-place.
The Amsoil 5w-30 I run in my 98 CSVT goes 15K mi with no sweat. Because I have good reason to believe that, even at 15K, I'm dumping perfectly good engine oil, the next change, I'm sending a sample to Cleveland Tech for a total workup.
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> All engine oils will darken with use. The best dino oil will darken much deeper and faster than the best synth oil. This is because the best dino oil volatilizes much faster and, in every other performance criterion, also is grossly inferior to the best synth oil.
> Make certain you're looking at the "circulating oil", ie, the oil that adheres to the dipstick no more than 5-10 minutes after engine shut-down .
Checking your oil after the car has been sitting on a level surface for a longer period of time will give you the most accurate reading of the oil level -- and the scariest picture of you oil's appearance. This is because the oil now on the dipstick is what's called "pan oil", ie, the 5%, lowest-of-the-low layer of oil in the pan where all the really skanky stuff settles to when the engine has been shut down for a while. The longer the shutdown, the skanky-er the pan oil becomes
> It's not about color. It's about clarity . Assuming you never greatly-exceed the recomended change interval for the oil you're using, if the circulating oil on the dipstick has the clear, dark brown color of "black" coffee, it's probably good to go. If its color looks more like Nestle's Chocolate syrup, change ASAP. And if it has the color of -- and sort of smells like -- asphalt, it's probably a good time to start writing the obitutary for your car that you'll soon be posting here.
