Gas Mileage

[misterp]

The GM Performance Parts sport exhaust catback is made by Borla - check this thread for more info.

 

Motor oil, use Mobil-1 5W-30 or 0W-30, I would not suggest 10W-30, you will not gain any protection and in fact will loose mileage when the oil is cold as well as increase startup wear over the years because it takes a couple seconds to get the main & rod bearings afloat on startup, and after 5-10 years all that startup wear begins to make a difference. Also remember that the oiling system in the LSx engines are backwards (the cam gets the oil first then the crank) so it takes even longer for pressurized oil to make its way to the crank at startup. Oil additives have come a long way in late years and I am now a firm believer in super-low viscosity synthetic base stocks that circulate immediately on start-up combined with proven additives to provide protection when hot, I use Mobil1 0W-30 in my SS for 50K-miles now and it's still whisper quiet; for all-out racing I use Mobile1 0W-40 unless the engine bearings are too loose to maintain pressure, then a 10W-* or 20W-* oil is called for. AMSOil also makes a superior product.

 

Quality gasoline makes a big difference, run premium fuel and use either Chevron, Shell, or Mobil. If the computer senses any detonation at all (most of which is inaudible) then your mileage will instantly go into the shitter as the PCM will panic and retard ignition timing until it thinks it's safe again to try using the high-octane timing table. A quality PCM tune will really help with both performance and mileage, a quality tune is the single best improvement you can purchase and will pay for itself over the life of the truck.

 

And welcome to the forum

 

Mr. P.

Edited January 12, 2007 by misterp (see edit history)

[CoolBlueSS]

Motor oil, use Mobil-1 5W-30 or 0W-30, I would not suggest 10W-30,

 

 

 

Mr. P.

<{POST_SNAPBACK}>

I'v e alway thought that a 0W-5W30 would be too thin for our part of the country. I know oil has come a long, long way in the last 20 or so years. I've been using 10W30 for years, but I may be thinking old school. You really think the 5W30 is that much better?

[misterp]

I'v e alway thought that a 0W-5W30 would be too thin for our part of the country. I know oil has come a long, long way in the last 20 or so years. I've been using 10W30 for years, but I may be thinking old school. You really think the 5W30 is that much better?

Hell no there is no such thing as "too thin" regarding engine startup - you want to immediately get those bearings afloat, especially on our engines where the bearing and skirt clearances are sub-.001". These engines are built for thin oil. The problem is that thin oils typically don't hold up worth a darn to heat, so that's why oil makers put in additive packages (to increase the oil's breakdown resistance) and why the brand of oil you choose is critical, you need a super-thin base stock that has a fantastic additive package. My personal recommendation for a full-on racing Gen-3 & 4 motor is Mobile1 0W-40, for serious street performance machine I use Mobile1 0W-30, and if I cannot find that (I live in the sticks ya' know) then I get Mobile1 5W-30 at Walmart - that's what I do. I've looked at all the other oil manufacturer's products of late and the only one superior is AMSOil, the rest of the stuff on the market, both over-the-counter and specialty companies, is not worth consideration in a Gen 3 & 4 motor IMO, especially their 0W-* products.

 

The base stock viscosity is going to depend mosly on initial bearing & piston skirt clearance, 10W-* is too thick for startup although it thins out after the first 3-4 minutes. As I said I've run Mobile1 0W-30 for 3 years now and my engine is still silent on startup and gets 80psi at 5K-RPM when hot. Now on more 'traditional' engine build setups where forged pistons are used (more initial running clearance) or the crank is turned down to employ running clearances somewhere around .0015" then yes I would probably use a 10W; and loose bearings (.0025"-.003") and full-race forged pistons (.004"-.006" cold clearance) I would use 20W-50.

 

Mr. P.

 

edit - high mileage motors I would also move up to 10W-*, 15W-*, or 20W-* depending on bearing condition.

Edited January 12, 2007 by misterp (see edit history)

[CoolBlueSS]

I'm using Castrol Syntec 10W30, as I've used Castrol for years with no problems. I ran convetional 10W30 in my old Poncho, and my old trucks, but I'm learning of the tighter tolerances on these engines after being on this board for a couple of years now. I may drop to 5W30 on my next change. Like I said, I still think old school sometimes.

[Fireman31]

Awesome where can I find this GMPP/Borla system your talking about because I'm considering buying some borla mufflers for better flow because I know flowmaster isnt known for there flow/performance and also what intake would you recommend? I'm a fan of K&N but am open on ideas for now. Right now I'm trying the shell 93 octane v power and its seems to me so far that my mileage has gone up quite a bit because I'm still at half a tank with about 180 on the tank so far and usually by this time of the week im down to a quarter or less so well see how she stacks up at the end of the tank. Thanks for the info and my truck is going to go into the shop hopefully next weekend or sooner for a oil change and im gonna put in mobil 10w30 like you recommended because im hopping on the throttle quite a bit but not usually to the peak though but I still want her to be protected as best she can because shes my baby and i like her well lubed lol. Also if i do go with some borla mufflers im thinking i might just punch out the cats with some borla muffler would make her sound sweet i think.

 

check this site for the GMPP cat-back info crateenginedepot.com

Edited January 13, 2007 by Fireman31 (see edit history)

[ssaman]

As for seafoam it can pretty much be put anywhere to do something diffrent. A buddy and used it through the vaccume line to clear any carbon build up in the engine out. we just poured about half a can into a cup and sucked it up through the vaccume line and then let it die. Let it sit for 30min or so then turned it back on. the exaust blew white smoke ( all of the build up ) out for about 5-7min. But that was on his camaro. seemed like it worked fine, helped the engine out and everything but who knows for sure.... oh well thats my exp. with seafoam.

[Bad Bowtie]

2004 GM trucks had NO EXTERNAL fuel filter. So 2003 had to be the last year for a easily servicable fuel filter. But since your truck has so few miles, I"d do what the guys above said 1st. Have truck alignment checked, run 28 psi in all 4 tires, add Chevron Techtron additive on your next fill-up of SUPER UNLEADED... Then report back to us bro. =o)

 

Seafoam fuel treatment can be had at most AutoZones, Pep Boys, O'Reillys, etc> It is a white metal can with red lettering, about $5.00 is the price here for like a single 10oz bottle? 1 can treats 8-20 gallons (or something like that). I've used 1/2 the can via the PCV valve hose, then poured the rest into half a tank of super unleaded. Then drove the truck for while. Seafoam helps to remove carbon deposites and clean the injectors too. It works on carburated and fuel injected vehicles. Heck my brother now adds a small mixture to his lawn mower and weed eater now......

 

[aaronjv]

i get about 14.7 average with a mix of city and highway.

[Prestoar]

I thru on an Outlaw CAI and mpg stayed about the same 16...just thru on my new tune from W4M and I have actually losted almost 1 mpg to 15 and thats with prem fuel. Only drove about 100 miles so far on the new tune though...maybe it takes a bit (adjust driving habits).