I recently purchased an 81 AMC Concord with a 258 I6. There are about 150K miles on it, and it will be a mix of city and highway driving before my next oil change. Any recommendations on brands/weights that would suit this engine?
AMC 258 (4.2L) I6
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I'd bet that the Rambler folks recommended 10W-30 when this thing was new.
The inline six used in many Jeep models over many years is a direct decendant of this engine, and I believe that 10W-30 was generally recommended for them.
Chrysler bought AMC mainly to get the Jeep brand.
Ironic that you live in Toledo, the home of Jeep.
The inline six used in many Jeep models over many years is a direct decendant of this engine, and I believe that 10W-30 was generally recommended for them.
Chrysler bought AMC mainly to get the Jeep brand.
Ironic that you live in Toledo, the home of Jeep.
The engine its self is very strong. The heads don't flow over about 2500 rpm and the Carter Carb never will idle smooth.
That was a nice engine back in the day. IIRC 10W30 is what they used.
T5 10w30 is a top choice.
X3 on the Rotella T5 or QS Defy 10w30 is another great choice.
How much different is the 4.2 I6 from the 4.0 I6? There are numerous UOA reports about the 4.0L engine to read in the UOA section.
I have rebuilt many AMC Jeep 2.5L/4.0L/258 engines and have found SOPUS lubricants to be a great choice. With Fall and Winter approaching, I would probably run good ol' Pennzoil 5W30 conventional.
Why is that?
Originally Posted By: 901Memphis
T5 10w30 is a top choice.
Originally Posted By: 901Memphis
T5 10w30 is a top choice.
My uncle had a 77 CJ7 with the 258; very good motor IMHO. I'd run Rotella 10W-30
Probably would have run 300K if everything around it didn't disintegrate.
I especially loved having the clutch disengagement mechanism fall out on the street as I drove by the house.
Probably would have run 300K if everything around it didn't disintegrate.
I especially loved having the clutch disengagement mechanism fall out on the street as I drove by the house.
Originally Posted By: kschachn
Why is that?
Originally Posted By: 901Memphis
T5 10w30 is a top choice.
A few reasons folks like T5, off the top of my head:
Add pack, healthy ZDDP. As a HDEO, it's not constrained like the sn PCEO are in the add pack department.
HTHS of 3.5 or more.
Cold performance is pretty close to T6 for most of us in US.
Semi-synthetic, so your less likely to have the "my older engine started leaking oil when I added full synthetic oil" syndrome.
It's easy to find and every day price is reasonable. (Downside with T5/6 is the 4qt jugs usually are shy of a OC. So you have to buy another gallon and hold on to it, or the the more expensive one quart bottles. Most buy a a single one quart the first time and then second time refill it from the gallon size to keep a quart in the vehicle for top off. You can mix T6 with T5 if needed.)
Plenty of data out there for your pre-use evaluation. SOPUS publishes decent range of data comparatively. Also voa's and plenty of uoa's are available.
Why is that?
Originally Posted By: 901Memphis
T5 10w30 is a top choice.
A few reasons folks like T5, off the top of my head:
Add pack, healthy ZDDP. As a HDEO, it's not constrained like the sn PCEO are in the add pack department.
HTHS of 3.5 or more.
Cold performance is pretty close to T6 for most of us in US.
Semi-synthetic, so your less likely to have the "my older engine started leaking oil when I added full synthetic oil" syndrome.
It's easy to find and every day price is reasonable. (Downside with T5/6 is the 4qt jugs usually are shy of a OC. So you have to buy another gallon and hold on to it, or the the more expensive one quart bottles. Most buy a a single one quart the first time and then second time refill it from the gallon size to keep a quart in the vehicle for top off. You can mix T6 with T5 if needed.)
Plenty of data out there for your pre-use evaluation. SOPUS publishes decent range of data comparatively. Also voa's and plenty of uoa's are available.
My grandmother bought a '79 Concord new with this same engine. It got Pennzoil 10w-30 until the tin-worm took it away a couple years ago. It still ran just fine.
Originally Posted By: artificialist
How much different is the 4.2 I6 from the 4.0 I6? There are numerous UOA reports about the 4.0L engine to read in the UOA section.
the 4.0 will run circles around the old 258
How much different is the 4.2 I6 from the 4.0 I6? There are numerous UOA reports about the 4.0L engine to read in the UOA section.
the 4.0 will run circles around the old 258
Thanks for all your replies!
I just took a 1980 AMC 258 out of a CJ-7 apart for the 12 counterweight crankshaft and 707 rods. The 12 weight crankshaft weights 66lbs! The 4 counterweight cranks they used in the 1981 thru 1990 AMC 258s, pretty much just in last year CJs and first year YJs(1987-1990) weighs an amazing to me 20lbs less at 46 lbs. A Jeep 4.0 crank of any year comes in at 55lbs. This 1980 258 crank I have has been ground -.010, for the rebuild the 258 had previously, but only needed a polish from machine shop. Rods need to be checked for stretch and straightness, and I would like to install new ARP bolts, then New Sealed Power 4.0 standard bore pistons will then be pressed on for a mere $40. Then Into my awaiting 2000 Jeep XJ 4.0 for what Im going to call it "Dirty Light Hone 4.5", if I had bore Her .020 or .030 She would be a 4.6Liter and .060 would make Her a Dirty OverBore 4.7, offset ground crank goes to 4.8Liter and take .125 out of Her Walls, stuff Chevy 4" pistons for a 5.0Liter FourPointOh!
This 4.5 Im building, with the Heavier 258 crank, is going in front of a AW4 4 speed auto, when It really should be going in my White 96 XJ in front of Her AX15, to get the most of the natural freewheel effect of 66lb crank. I can always Swap motors, but then Ill have to swap heads cause of the coil pack bosses...
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