Another oil thread!

Miles or months?

I never understood the months part. Manual says 5,000 miles or six months. If you've driven less than 5,000 miles but your oil is six months old, change it anyway. Why?

If I put in fresh oil (real motor oil, not used cooking oil), and didn't drive my vehicle at all for six months, would the oil go bad? The oil wouldn't deteriorate sitting on the store shelf, so I would think it's also just fine sitting in my oil pan for six months.

So why is the time factor important?

And I just have to ask also, how does dino vs synthetic affect the time factor?

 

Good question but I use "time" when changing my oil. I change mine once a year using AMSOIL but change filters every 7,500 miles. AMSOIL warranties their 'Signature' oil for 1 year or 25K miles, whichever occurs first.

 

http://www.bobistheoilguy.com/

Good information here. Some consider this as the holy grail of oil.

 

Thank you for making me smarter!

I didn't know motor oil came with a warranty, so that's interesting. And of course, the vehicle has a warranty that you could void by not changing oil regardless of your logic.

Jimmyh's link was especially useful. I didn't read the whole thing, but I found 'oils form waxes at [low] temperatures,' which makes for 'permanent thickening' (Motor Oil 104). So if your car spends time outside in the winter, your oil will degrade even if you don't drive it. In Motor Oil 102, it says oil thins with use (partly from absorbing combustion products, but that's miles, not time), and thickens with time, especially if exposed to wide temperature swings (probably the wax thing).

OK, I'm a believer. The time intervals are not just made up. I don't think I've ever run out the clock before I hit the mileage interval, but it's still good to know.

 

Many years ago I service small engines - types that only get used part of the year ( I.e, Lawnmowers in the northern states). I was taught that the oil really needs to be changed even if it has low hours on the oil. Reason being is that even just a little blow by from the piston rings contaminates the oil and causes reactions between the gases, metals, oil, etc. and if left to sit for long periods it can turn acidic and begin to deteriorate the internal parts. Best to change oils as specified.

 

I was a grease monkey in the Coast Guard for 22 years. We never changed our lube oil based on time, only engine operating hours (small engines) or when the lab told us to (main diesel engines & reduction gears).
If you're still under warranty however, follow the schedule in the owners manual.
Edit: I use Mobile-1 & Toyota oil filters, change the oil & oil filter every 10000 miles with a filter change at 5000 miles.

 

The oil gets contaminated the moment you put it in your truck..... Not only does it mix with the oil left over that didn't drain out, but all the other 'things' in your engine (sludge, moisture, leftover combustion contaminates, etc)

With each oil change, you are removing 'contaminants'. If your engine is exposed to too much contaminants for too long.... the lubrication won't be as effective.

I personally change mobile 1 & filter every 5,000miles (twice a year normally). When we used to own a Jeep & Corvette that rarely broke 3-4000miles in a year....I'd change the oil once a year.

 

Thanks for posting this link. Very good information...