spokane.yota.man

i was changing my oil last night and as i was just about finished pouring in the last bit of oil from the 5qt bottle of castrol gtx 5w-30 i noticed it looked darker then usual. i had another 5qt bottle that was half full from a few months ago and i compared it to that oil and it was definitely darker. they were the exact same product, even bought from the same store, just a few months apart. anyone ever have this problem before? it wasn't like used oil but it was definitely darker then my other bottle. the consistency was about the same so i went ahead and left it in (for now). i've always used castrol but this has me thinking about a possible switch. i emailed castrol to see what they have to say but i'm sure i'll get some bs saying that color variation is normal. but in 10 years of using castrol i have never noticed it.

mt_goat

I have noticed it on some Napa full synthetic that had been sitting around for over a year. I think some of the additives settle out into layers, after a few quarts I shook up the rest of the bottles and didn't notice it after that. Something to think about when using big jugs of oil.

spokane.yota.man

i got an email back from castrol (only took an hour to respond, thats pretty impressive) here is what they had to say:

"Thank you for contacting Castrol. Recent formulation changes in Castrol engine oil have resulted in a change in appearance of our products with the color being noticeably darker. A darker product color is perfectly normal and continues to represent Castrol engine oil of the highest quality and performance. The change in color is due to the selection of new and improved additive technology to meet the ILSAC GF-5 requirements for better performance, especially in the area of deposit control protection."

i researched the gf-5 and it is a new standard that went into effect in october 2010. supposedly it has better additives that increases the performance in all aspects. i am going to verify the fill batch number from the bottle with castrol to make sure that is in fact the reason it was darker. sounds like it's ok though and have nothing to worry about. i am use to oil looking a certain way and so it was quite a surprise to see it differently. i am interested to hear if anyone else has noticed this change.