I just installed a secondary fuel filter made by lubrication specialist: http://www.lubricationspecialist.com http://www.the**********.com/reviews/landuytfuelfilter.htm

Install was moderately difficult for an amateur like me, but I got through it. My first attempt was to install the unit pre-OEM, but I couldn't get a prime after install. I knew there was a vacuum leak somewhere but couldn't find it. I switched to post-OEM so the filter would be pressurized and I could see where the diesel was leaking. Found the leak at one of the banjo bolts on the filter, was a bad copper washer. Fortunately the kit comes with extras, probably damaged in shipping. I'd rather have the filter installed pre-OEM but I was so burnt out after switching it I didn't feel like putting it back. Maybe later.

I got this filter because it looked much easier to install and the owner convinced me it was better than the racor pre-filter. I agree that the install was easier, but one thing I'm concerned about, that I didn't think of when I bought it, is having the extra fuel lines running across the engine. May be more potential for leaks/fire if there is a problem, having had a car burn up in the past from a fuel leak, I think about these things. Also, the instructions are not real clear on where to run the fuel lines on the new LMM. Company needs to update the pictures. Not being clear on exactly where to run the fuel lines, after installation I took the truck out, turned on the AC and heated up the engine to operating temp, popped the hood and made double sure the fuel lines weren't sitting on, or rubbing anything that could cause problems in the future. Looks good.

Now here's the weird thing. I have 950 miles on the truck and I've been babying it making sure I follow the break in suggestions. I've been getting 12.8 mpg on the computer and about 15 hand calc'd-driving very conservatively. After installing the filter I ran the truck hard for the first time. Did some to the floor accelerations getting on the freeway, powered up some hills etc. to get the engine nice and hot (BTW the power these things have is awesome). Yesterday on the way to work I got 19mpg @55mph on the computer and 17.8@65mph. On a long stretch at 50mph I was getting 20! Haven't done hand calc yet.

I know it can't be the filter, so I guess there is something to all the guys saying that running the truck hard increases the MPG? Hmmmmm....

IMO, you need to drive the shit out of it during break in.

break it in the way you want it to run if you baby that thing it will be a turd

Some have reported small increases in mpg with added filtration, but typically a lift pump seems to help as much or more. The lines across the engine is a definite concern as is the fact that the filter is subject to engine vibration/heat, plus when you drain/bleed if you spill it's on the engine.

bigwoo,how about some pics where you installed it.I've been considering this unit as well. Thanks

While I didn't notice an increase in MPGs, I do run the Lubrication Specialist Duramax auxiliary filter system on both of my LBZs - pre-OE filter. It does make for a super simple filter change, as well as WIF drain checks (I use a small clear plastic cup to check). I changed my auxiliary filter at 10K miles and the last two were black only on the bottom 1/8 of the filter media, and my OE filter monitor, this interval, is still at 18% with 15K miles (I hate changing the OE filter, so anything that helps extend the filter change intervals is a big plus in my book). ;) I plan on going a little further on the auxiliary fuel filter this next interval.

You can see how I routed the supply line in the front, the feed line to the OE filter is routed along the AC line behind the resonator...zip tying everything along the way.

thanks vin63

bigwoo,how about some pics where you installed it.I've been considering this unit as well. Thanks

I'm at work for a few days but asap I'll put up some pictures

You can see how I routed the supply line in the front, the feed line to the OE filter is routed along the AC line behind the resonator...zip tying everything along the way.

Your's is run a bit different than mine, looks like your is pre-OEM. I'll post a picture of mine as soon as I can.

Mine is installed post OEM, I've got to change it though. Since the first filter in line will be changed more often, the lower cost and ease of changing the lubrication specialist filter will make it worth digging in there again to re-route the lines. Doesn't look like I'll have time to do it before my first test run south of the border though.

I just bought a spare OEM filter. Can't believe how expensive they are at the local auto parts store! :mad: Time to do some internet shopping!

Your's is run a bit different than mine, looks like your is pre-OEM. I'll post a picture of mine as soon as I can.

Mine is installed post OEM...!

Yep, mine is installed pre-OE. This way I figured I would have to change the (easier to change) auxiliary filter about 1.5 to 2 times as often as the OE filter. It's the best modification, hands down, that I've done to any of my diesels.

Here's how I ran my fuel lines. Sorry it took so long (been working waaay to many hours). One fuel line runs toward the front of the engine just behind the alternator, the other toward the rear just under the air conditioning tube. When I change it to Pre-OEM I'll only need to re- route the last foot or so to align with the proper OEM filter fittings.

I noticed your truck has a passenger side fender brace above the battery. Mine does not