Synthetic oil question
JK Freak
Joined: Jun 2011
Posts: 723
Likes: 2
From: Murrieta, CA
My Jeep is not my daily driver. I run Amsoil that is rated for 12K or one year. I Change it annually or 10k, every other tire rotation. My manual says 8k for dino stuff. High performance filter is rated for 15k, so it goes at each oil change.
My car oil goes 22.5K with filter replacement every 7500 miles.
My car oil goes 22.5K with filter replacement every 7500 miles.
JK Super Freak
Joined: Feb 2009
Posts: 1,488
Likes: 1
From: Sydney, Australia
Another thing that affects the duty cycle of oil is the length of time the motor is running between cold start-up & shut-down. Many people start their car & then only drive it a few miles to work, etc before shutting it down again and the oil rarely reaches operating temperature (engine oil can take up to 20 or 30 minutes to achieve full operating temperature depending on environmental conditions). While the motor is warming up it produces a lot of water condensation (seen as steam & water coming out the tailpipe) and this enters the crankcase and contaminates the oil.
Usually whan a motor has fully warmed up and reached full operating temperature (not just the coolant which happens quickly thanks to the thermostat, but the engine oil as well which takes considerably longer) this condensation in the crankcase evaporates. However if the oil is never given a chance to fully heat up then this water will contaminate the crankcase, leading to corrosion and acid build-up and effectively shortening the maximum lifespan of the oil by more than half. And since most engine wear is experienced during warm-up from cold starts, you want your oil to be in tip-top condition to help lubricate and protect the rings, bearings and valvetrain during this time.
So in a nutshell: longer highway trips, good; short city trips (particularly in winter), bad. It's the reason why you'll often see taxi cabs with over half a million miles on the clock with the original engine & transmission still in them, as they spend most of their lives on the road and their motors at normal operating temperature so they rarely get a chance to cool down fully and thus experience these cold-start issues outlined above (usually the only time they're turned off at all is to gas up and during routine service).
Usually whan a motor has fully warmed up and reached full operating temperature (not just the coolant which happens quickly thanks to the thermostat, but the engine oil as well which takes considerably longer) this condensation in the crankcase evaporates. However if the oil is never given a chance to fully heat up then this water will contaminate the crankcase, leading to corrosion and acid build-up and effectively shortening the maximum lifespan of the oil by more than half. And since most engine wear is experienced during warm-up from cold starts, you want your oil to be in tip-top condition to help lubricate and protect the rings, bearings and valvetrain during this time.
So in a nutshell: longer highway trips, good; short city trips (particularly in winter), bad. It's the reason why you'll often see taxi cabs with over half a million miles on the clock with the original engine & transmission still in them, as they spend most of their lives on the road and their motors at normal operating temperature so they rarely get a chance to cool down fully and thus experience these cold-start issues outlined above (usually the only time they're turned off at all is to gas up and during routine service).
Last edited by JKlad; Nov 30, 2011 at 05:35 PM.
Thread Starter
JK Enthusiast
Joined: Jun 2011
Posts: 288
Likes: 0
From: Katy, TX
Originally Posted by JKlad
Another thing that affects the duty cycle of oil is the length of time the motor is running between cold start-up & shut-down. Many people start their car & then only drive it a few miles to work, etc before shutting it down again and the oil rarely reaches operating temperature (engine oil can take up to 20 or 30 minutes to achieve full operating temperature depending on environmental conditions). While the motor is warming up it produces a lot of water condensation (seen as steam & water coming out the tailpipe) and this enters the crankcase and contaminates the oil.
Usually whan a motor has fully warmed up and reached full operating temperature (not just the coolant which happens quickly thanks to the thermostat, but the engine oil as well which takes considerably longer) this condensation in the crankcase evaporates. However if the oil is never given a chance to fully heat up then this water will contaminate the crankcase, leading to corrosion and acid build-up and effectively shortening the maximum lifespan of the oil by more than half. And since most engine wear is experienced during warm-up from cold starts, you want your oil to be in tip-top condition to help lubricate and protect the rings, bearings and valvetrain during this time.
So in a nutshell: longer highway trips, good; short city trips (particularly in winter), bad. It's the reason why you'll often see taxi cabs with over half a million miles on the clock with the original engine & transmission still in them, as they spend most of their lives on the road and their motors at normal operating temperature so they rarely get a chance to cool down fully and thus experience these cold-start issues outlined above (usually the only time they're turned off at all is to gas up and during routine service).
Usually whan a motor has fully warmed up and reached full operating temperature (not just the coolant which happens quickly thanks to the thermostat, but the engine oil as well which takes considerably longer) this condensation in the crankcase evaporates. However if the oil is never given a chance to fully heat up then this water will contaminate the crankcase, leading to corrosion and acid build-up and effectively shortening the maximum lifespan of the oil by more than half. And since most engine wear is experienced during warm-up from cold starts, you want your oil to be in tip-top condition to help lubricate and protect the rings, bearings and valvetrain during this time.
So in a nutshell: longer highway trips, good; short city trips (particularly in winter), bad. It's the reason why you'll often see taxi cabs with over half a million miles on the clock with the original engine & transmission still in them, as they spend most of their lives on the road and their motors at normal operating temperature so they rarely get a chance to cool down fully and thus experience these cold-start issues outlined above (usually the only time they're turned off at all is to gas up and during routine service).
JK Jedi Master
Joined: Feb 2008
Posts: 12,907
Likes: 185
From: Maine
Mobil 1, no additives.
6,000 miles, or each April & October. Since I drive it about 12,000 miles a year, the two always coincide. The OCI seems to be pretty close to my schedule, too, although I pretty much ignore it, and reset it, if it comes on way too soon.
6,000 miles, or each April & October. Since I drive it about 12,000 miles a year, the two always coincide. The OCI seems to be pretty close to my schedule, too, although I pretty much ignore it, and reset it, if it comes on way too soon.
JK Freak
Joined: Sep 2011
Posts: 518
Likes: 1
From: Katy, TX
Originally Posted by JKlad
Another thing that affects the duty cycle of oil is the length of time the motor is running between cold start-up & shut-down. Many people start their car & then only drive it a few miles to work, etc before shutting it down again and the oil rarely reaches operating temperature (engine oil can take up to 20 or 30 minutes to achieve full operating temperature depending on environmental conditions). While the motor is warming up it produces a lot of water condensation (seen as steam & water coming out the tailpipe) and this enters the crankcase and contaminates the oil.
Usually whan a motor has fully warmed up and reached full operating temperature (not just the coolant which happens quickly thanks to the thermostat, but the engine oil as well which takes considerably longer) this condensation in the crankcase evaporates. However if the oil is never given a chance to fully heat up then this water will contaminate the crankcase, leading to corrosion and acid build-up and effectively shortening the maximum lifespan of the oil by more than half. And since most engine wear is experienced during warm-up from cold starts, you want your oil to be in tip-top condition to help lubricate and protect the rings, bearings and valvetrain during this time.
So in a nutshell: longer highway trips, good; short city trips (particularly in winter), bad. It's the reason why you'll often see taxi cabs with over half a million miles on the clock with the original engine & transmission still in them, as they spend most of their lives on the road and their motors at normal operating temperature so they rarely get a chance to cool down fully and thus experience these cold-start issues outlined above (usually the only time they're turned off at all is to gas up and during routine service).
Usually whan a motor has fully warmed up and reached full operating temperature (not just the coolant which happens quickly thanks to the thermostat, but the engine oil as well which takes considerably longer) this condensation in the crankcase evaporates. However if the oil is never given a chance to fully heat up then this water will contaminate the crankcase, leading to corrosion and acid build-up and effectively shortening the maximum lifespan of the oil by more than half. And since most engine wear is experienced during warm-up from cold starts, you want your oil to be in tip-top condition to help lubricate and protect the rings, bearings and valvetrain during this time.
So in a nutshell: longer highway trips, good; short city trips (particularly in winter), bad. It's the reason why you'll often see taxi cabs with over half a million miles on the clock with the original engine & transmission still in them, as they spend most of their lives on the road and their motors at normal operating temperature so they rarely get a chance to cool down fully and thus experience these cold-start issues outlined above (usually the only time they're turned off at all is to gas up and during routine service).
JK Newbie
Joined: Nov 2011
Posts: 15
Likes: 0
From: Utah
Lots of good info in this thread. I am a 5k mobil guy these days. That said, I used to run auxillary filtration and did the Blackstone Labs deal. I would put 25k on the amsoil with 5k filter changes in the primary and 12.5k on the secondary. Labs were always good even at 25k. This was in a 4.0l '93YJ. We did the 5k deal on a '92XJ with dino and put 264K on her. Still ran like new when we sold her. The real key is to pick a plan and stick with it. Oil lasts much better than many would lead us to believe. As mentioned above, short trips are dealth to oil, emissions systems, etc. If you do a lot of short trips, take it out routinely and run it a little hard at full temps occaisionally! And change it every 5...
JK Junkie
Joined: Dec 2008
Posts: 2,191
Likes: 6
From: Boston, MA
OP:
as for adding something to the oil (lucas, etc.) You're just diluting an engineered product. If you're using a quality oil, why bother? My understanding is that most of those oil-additives just "thicken" it up. But I'm no expert.