Well, BITOGers, I suppose you know the drill. I want a highly-recommended oil for my old Jeep, and I also want some answers about the dreaded "stuff I heard" on the errornet.
Vehicle Information:
1994 Jeep XJ Cherokee
Chrysler/AMC 4.0 liter L6
Aisin AX15 5-Speed Manual Transmission
217,000 miles on the clock
The 1994 Factory Service Manual says to use 5W-30 or 10W-30 motor oil, of API SG grade, Energy Conserving or Energy Conserving II. It clearly states that non-detergent oils and straight mineral oils must NEVER be used to lubricate a Jeep engine. It recommends OCIs of 3,000 to 7,500 miles for different driving conditions.
I live in Southern Idaho (high-desert climate) and go to school in Moscow, ID. The climates are similar, ranging from -20* F to 120* F in temperature. It is not uncommon for it to be below freezing in the morning and above 70*F in the same day.
My driving style is typically fairly normal/conservatively, but I do have hard acceleration runs every once in a while. I drive it harder in the city than I do on the highway. I take it on trails and offroad, also, so the engine operates at a very low RPM range at these times. My daily drives are extremely varied, with short trips in the city and long (400+ mile) trips on the highway.
My Jeep has 217,000 miles on the clock, but runs very good. I don't just change the oil, but work on it frequently to keep it running well. It is my only vehicle, so it must run good and be very reliable. I replace worn-out parts well before they break or cause troubles. I flush the engine coolant every two years. I'm a gearhead, so I'm always peeking under the hood to check connections and listen to the engine. My engine has a lot of valvetrain noise, like most 4.0L L6 engines have. It sounds diesel-ish under the hood.
I've run Valvoline MaxLife 10W-30, PYB 10W-30, and Mobil 1 5W-20 in the past. I used to change the oil every 3-4k miles, especially with PYB. With the full synths, I go 5k-7k OCIs. I run Purolator PureOne, Wix, Bosch, and Mobil 1 oil filters. I prefer full-synthetic motor oils, because they give me better fuel mileage and the engine oil comes out much cleaner at oil changes. My last oil change interval at 5k miles of M1 5W-20 came out a lighter brown. It had never been that clean before. I've run the same oil for the past 3 OCIs, from 205k miles on. It has been getting a consistent 22-24 MPG with the M1 5W-20 oil.
I'm due for an oil change in about 2-3k miles, and I've already picked up another Puro P1 filter and a bottle of M1 5W-30 High Mileage motor oil ($22.49/5qts at wally-world). I had to drop a quart of Lucas stop-leak in the engine because my oil filter adapter started leaking a decent amount. I would like to change it soon, because I know that using their "heavy duty oil stabilizer" ain't exactly good for the engine.
What motor oils does everyone here recommend? I've seen many guys on the forums running 15W-40 oils, which are diesel-grade. Some think that the ol' AMC engine is a tractor engine, so it needs super-thick oils. These come from SWAGs, I think, from reading about the drop in ZDDP in newer oils, when in fact the full-synths have 800-900 PPM zinc or whatever, with the hi-mileage stuff having more in many cases. I think that if you used 15W-40 or (in some cases, yes) 20W-50 oil(!!!), it would kill a lesser engine. I think they're nuts to run anything thicker than 10W-30, especially after they've read and (I assume) understood Motor Oil University! I've also caught flak from them for running M1 motor oils, because supposedly it tears up the engine and (OMG!) CAMshaft because "the 4.0L is a flat-tappet engine, OMG you're going to destroy it!", causing excess scuffing and all these things that probably would have detonated my Jeep a while back...
I will be sending an oil sample to Blackstone after this OCI, btw. I want to know if running that 5W-20 is bad or not.
Let the discussion begin!
Rob
Vehicle Information:
1994 Jeep XJ Cherokee
Chrysler/AMC 4.0 liter L6
Aisin AX15 5-Speed Manual Transmission
217,000 miles on the clock
The 1994 Factory Service Manual says to use 5W-30 or 10W-30 motor oil, of API SG grade, Energy Conserving or Energy Conserving II. It clearly states that non-detergent oils and straight mineral oils must NEVER be used to lubricate a Jeep engine. It recommends OCIs of 3,000 to 7,500 miles for different driving conditions.
I live in Southern Idaho (high-desert climate) and go to school in Moscow, ID. The climates are similar, ranging from -20* F to 120* F in temperature. It is not uncommon for it to be below freezing in the morning and above 70*F in the same day.
My driving style is typically fairly normal/conservatively, but I do have hard acceleration runs every once in a while. I drive it harder in the city than I do on the highway. I take it on trails and offroad, also, so the engine operates at a very low RPM range at these times. My daily drives are extremely varied, with short trips in the city and long (400+ mile) trips on the highway.
My Jeep has 217,000 miles on the clock, but runs very good. I don't just change the oil, but work on it frequently to keep it running well. It is my only vehicle, so it must run good and be very reliable. I replace worn-out parts well before they break or cause troubles. I flush the engine coolant every two years. I'm a gearhead, so I'm always peeking under the hood to check connections and listen to the engine. My engine has a lot of valvetrain noise, like most 4.0L L6 engines have. It sounds diesel-ish under the hood.
I've run Valvoline MaxLife 10W-30, PYB 10W-30, and Mobil 1 5W-20 in the past. I used to change the oil every 3-4k miles, especially with PYB. With the full synths, I go 5k-7k OCIs. I run Purolator PureOne, Wix, Bosch, and Mobil 1 oil filters. I prefer full-synthetic motor oils, because they give me better fuel mileage and the engine oil comes out much cleaner at oil changes. My last oil change interval at 5k miles of M1 5W-20 came out a lighter brown. It had never been that clean before. I've run the same oil for the past 3 OCIs, from 205k miles on. It has been getting a consistent 22-24 MPG with the M1 5W-20 oil.
I'm due for an oil change in about 2-3k miles, and I've already picked up another Puro P1 filter and a bottle of M1 5W-30 High Mileage motor oil ($22.49/5qts at wally-world). I had to drop a quart of Lucas stop-leak in the engine because my oil filter adapter started leaking a decent amount. I would like to change it soon, because I know that using their "heavy duty oil stabilizer" ain't exactly good for the engine.
What motor oils does everyone here recommend? I've seen many guys on the forums running 15W-40 oils, which are diesel-grade. Some think that the ol' AMC engine is a tractor engine, so it needs super-thick oils. These come from SWAGs, I think, from reading about the drop in ZDDP in newer oils, when in fact the full-synths have 800-900 PPM zinc or whatever, with the hi-mileage stuff having more in many cases. I think that if you used 15W-40 or (in some cases, yes) 20W-50 oil(!!!), it would kill a lesser engine. I think they're nuts to run anything thicker than 10W-30, especially after they've read and (I assume) understood Motor Oil University! I've also caught flak from them for running M1 motor oils, because supposedly it tears up the engine and (OMG!) CAMshaft because "the 4.0L is a flat-tappet engine, OMG you're going to destroy it!", causing excess scuffing and all these things that probably would have detonated my Jeep a while back...
I will be sending an oil sample to Blackstone after this OCI, btw. I want to know if running that 5W-20 is bad or not.
Let the discussion begin!
Rob
