the filter will drain back 1/2 of its oil regardless of the make....there is no anti-drain back valve on the outlet (threaded portion). It will drain out of the threaded hole into the oil galley until the filter is a little less then half full. With the large FL-1 filter you have to overfill by 1/2 quart.

 

Okay, maybe not totally full, but there will be oil in a good quality filter and none in a crappy one. I've got first-hand experience with this. In other words, the fram will be EMPTY and a good filter will have a fair amount of oil come out once it's unscrewed a little bit.

 

The way I look at it, if oil level is between the 2 marks on the stick, the oil level is perfect. Using a FL-1A and 6 qts of oil, oil level is perfect.

 

?I few days ago I talked to mechanic, installing GM V8 in Wrangler. He was also doing conversion of NV231 tofit to GM transmission.

 

It probably won't hurt anything but your still running 1/2 quart low. If your dip stick is halfway between the min/max lines it will be on the min line after the engine starts and the filter re-fills. The volume of the FL-1 is double the 090 so you need to compensate for that.

 

I was poking fun at Ford products. I have no problem with GM.

 

I'm not so sure about running 1/2 qt low. 1/2 qt low would mean the oil level is below the bottom mark, no? U don't check oil level with the motor running....u check it motor off and after sitting a bit. Probably have to be 3-4 qts low to uncover the oil pick-up in the sump in a tight turn or hard stop. Between the 2 marks on the stick is perfect. Below the bottom mark is too low and above the top mark is over filled. Again, the range between the 2 marks is perfect. If the range between the 2 marks wasn't perfect, there would only be 1 mark on the stick, no?.

 

To use a 51515 Wix do you need a different oil filter adapter? Or does it screw on just like the regular Wix/Mopar size? Is the only difference with the 51515 Wix is that you hold more oil?

 

Just to clarify:

The 91 and later Jeeps will accept the 51515.

87 to 90s are metric thread and will not accept it.

That said, you can change the threaded nipple that the oil filter screws on to on an 87 to 90 to the 91 and later and it works perfectly. The nipple is less than $5 at the dealership.

 

Yes, the 51515 does hold more oil and has more square inches of filtration area than its smaller cousins.

Cruiser54 has summarized the fitment issues nicely.

 

Great, thanks. I have a 98 and may try the larger filter next oil change.

 

Yes you are correct but those marks are assuming that you have the OEM filter. With the larger filter you add an extra 1/2 qt. When you check the oil level after the engine has been off long enough for the oil to drain back out of the filter your dipstick will show 1/2 quart above full....this is normal!

 

Actually, the difference between the large capacity filter and the standard filter is that the larger filter has a capacity of approximately 25% more. You don't add a 1/2 quart more oil when using the larger filter. The volume of one (1) quart of liquid is 57.75 Cu. In. If the filters we're talking about had no internals, the large filter (WIX 51515) would have a capcity of 54.48 Cu. In. and the smaller filter (WIX 51085) would have a capcity of 40.29 Cu. In. The difference being the larger WIX is 14.19 Cu. In. larger. But they do have internals which drastically reduces the filter fluid capacity. I'm too lazy to try and figure out exactly how much oil each filter would actually hold.

When the engine has been off long enough, all the oil in the filter does not drain back into the engine due to the anti-drain back valve feature in the filter. (Early 4.0's with the near vertical filters may drain more than the later horizontal filters.)

The difference you would see on the dip stick between the large filter and the standard filter doesn't amount to a pinch of chit...provided you fill the oil pan to the full mark on the dipstick after oil change and subsequent intial running of the engine.

I need a beer...

 

When the big FL-1A filter is used and 6 qts are added, the oil level is perfect (between the 2 marks). I might also clarify that the FL-1A oil filter is for the later model XJs with SAE threads, not the early models with metric threads (not sure what year the change was). Over filled is over filled.....and not normal.

 

Not need to do a conversion, there is a NP231C that comes/came in the GM vehicles. Had one in my wifes 97 S10 Blazer.