What is a better gauge to change the oil, time or mileage? I only average about 600 miles a month on "da Rover". I use Mobil 1 5w-40. I read Spike write many times to change every 5,000 miles; but what about the old saying of changing the oil every three months? In a three month period I only drive about 1,800 miles. It does get driven just about every day or every other day, just not for long periods of time or mileage.

Thoughts?

 

Change it every 6 months and dont worry about it.
I change mine every 5,000 miles because I also use Mobil 1 but it is my daily driver.
You are either doing lots of short trips or only driving it once a week.
So every 6 months, if you used dino oil then every 3 months.

 

i will change the oil next month in the rover. i use amsoil. it also just so happens that next month will be 6 months of ownership and i might achieve 3k miles in that time. my rig is not my daily ride.

in my duc i change it twice yearly but more often if my riding is more aggressive.

 

Time is not a factor with synthetics. Dirty oil from mileage is the only problem.

 

What is Dino oil? I use Royal Purple dang I better check I think that's synthetic!
I'm with you mileage and I go every 3,000 although I think up in Idaho I could go 5,000 easy, but in AZ if you didn't have black oil you had no oil!

 

You can go 5k with RP. The purple dye makes it look darker than others.

 

RP is a synthetic,,,

and true with synthetics over organic oils you can change it over a longer period of time,,, but it will get dirty in that synthetics can filter out and hold crud in its molecules.

 

Dino oil is dinosaur oil, in other words conventional motor oil.

And yes time is a HUGE factor, even with full synthetics, it still gets contaminated with blow by gases, water, etc.
This happens more so with frequent short trips where the engine cant get hot enough to evaporate these things out of the crankcase.
One of the jobs of the PCV (positive crankcase ventilation) is for these gases/water vapor to be sucked out of the crankcase and be burned off inside the engine, in the old days they just vented these gases to the outside air.
Like I said, if you use dino oil you need to change it every 3 months because it cant hold up to this kind of contamination, full synthetic can.
Royal Purple is a good motor oil, so is Mobil 1, so is Castrol Syntec and Penzzoil Platnum.
Two things will kill a engine quick, frequent short trips and lack of oil changes.
Engines like to run, that is their sole purpose in life, to get hot.
Mobil 1 has a extended life motor oil, good for 15,000 miles or 12 months, whichever is sooner, that is the oil that I use and I change it every 5,000 miles even though they guarantee it to be good for 15k.
There is a fine line between changing the oil to late and wasting money by changing it to often.

 

I'm with Spike!
Mobil 1 Synth TD 5W40 Winter HTHS 3.9
Mobil 1 Synth HM 10W40 Summer HTHS 4.2
Regular oil @ 3000K
Synth @ 5000K

 

I use Mobil 1 10-30 and change it every 5000 miles. I was going to switch to Royal Purple but decided to stay with Mobil 1 when I saw RP was up to $9 a quart and I can get the 6 quart case of Mobil 1 for under $35 at Costco. When I first started using RP I bought it in 5 gallon pails and paid $17 a gallon.

Use a good filter such as the Mobil 1 M1-301 or K&N HP3001 that are a little larger for extra filtering capacity. The K&N filter is nice because it has a nut welded to the bottom to make it easier to remove. No need for a filter wrench. On the Discovery it's not a huge deal to use a filter wrench but some vehicle it's a lot easier to get a ratchet with a 1" socket in there than it is a filter wrench.