Regular vs Premium Gas

"Osiris - I can haz Euro spec?" (o51r15)
03/14/2014 at 12:05 • Filed to: None

So I was driving the truck and realized I need gas. Partly because the little light that says "Holy shit man, I need a refill!" came on. Normally I don't let it go below a half tank but I've been driving a lot lately for work. Now my question is, I have the 5.9L Magnum engine in my Dakota. Would it be better to use Premium gas or should I just stick with the 20 cents a gallon less Regular?

Edit: I guess I should have mentioned that the 2000 Dodge Dakota was never offered (so far as I've been able to tell) with a manual and a 5.9L Magnum. That's why I'm asking.

DISCUSSION (25)

HammerheadFistpunch > Osiris - I can haz Euro spec?
03/14/2014 at 12:06

here is the rule. Unless it DEMANDS premium, you are always better with regular.

Osiris - I can haz Euro spec? > HammerheadFistpunch
03/14/2014 at 12:07

Is there a website that I could go to and find out if that engine requires premium?

Nibbles > Osiris - I can haz Euro spec?
03/14/2014 at 12:07

Your compression ratio is 9.1:1. Regular is fine - it's what the engine was built for; if you put premium in you'll probably have unburnt fuel.

Hey, also, guess what?! I'm chatting with another guy (who owns that Taco Pre Runner I posted about) whose dad had a 1999 Dakota 5.9 manual. Really starting to wonder how these trucks existed - he said he has the build sheet somewhere and will bring it to me if he can find it.

HammerheadFistpunch > Osiris - I can haz Euro spec?
03/14/2014 at 12:08

owners manual, inside of the filler door, near the fuel release.

crowmolly > HammerheadFistpunch
03/14/2014 at 12:09

Nailed it.

dogisbadob > Osiris - I can haz Euro spec?
03/14/2014 at 12:10

Regular

Oh wow premium is only 20c more over there? In NJ the price difference is 40-50c per gallon :O

jariten1781 > Osiris - I can haz Euro spec?
03/14/2014 at 12:10

If you're not knocking just use regular.

The 5.9s did not have knock sensors so if you're knocking use a higher octane and go figure out why.

Party-vi > Osiris - I can haz Euro spec?
03/14/2014 at 12:10

Your engine has a knock sensor and can adjust timing. Go with regular. You're not going to see any increase in performance with premium gas, it will only ensure your engine performs as it should.

FJ80WaitinForaLSV8 > Osiris - I can haz Euro spec?
03/14/2014 at 12:11

I would bet a sizable amount of money that your dakota calls for regular.

M54B30 > Osiris - I can haz Euro spec?
03/14/2014 at 12:12

No owners manual?

liquid_popcorn > Osiris - I can haz Euro spec?
03/14/2014 at 12:12

Doesn't it say which octane rating is required right near the filler door? Or in the manual?

Osiris - I can haz Euro spec? > dogisbadob
03/14/2014 at 12:12

Military base prices are usually a little closer than off base prices.

Osiris - I can haz Euro spec? > liquid_popcorn
03/14/2014 at 12:16

The engine was swapped in by a previous owner. The 5.9L wasn't offered with the manual in 2000.

Osiris - I can haz Euro spec? > Nibbles
03/14/2014 at 12:17

Awesome! Thanks! And yea, I've never found anywhere that can tell me if the 5.9L was offered with the manual. So I've assumed it's been swapped. Works for me, but makes it hard to research the truck a bit.

Nibbles > Osiris - I can haz Euro spec?
03/14/2014 at 12:21

Well I can almost guarantee you have a NV3500 transmisison. The NV4500 wouldn't fit in the Dakota without tunnel and firewall modifications, which would be quite noticeable under the hood. But yeah you're not the only one with a seemingly factory 5MT 5.9

Osiris - I can haz Euro spec? > Nibbles
03/14/2014 at 12:27

I've only heard of a couple. I wonder if it was an extremely small run of them and maybe I have a semi-rare truck. Awesome!

Meatcoma > dogisbadob
03/14/2014 at 12:28

12-15c difference between reg and mid, as well as mid and prem at most places here in the midwest. One place it's 30c diff between reg/plus/prem. We get 87/89/91, sometimes you can find a place with 93 but it's rare.

liquid_popcorn > Osiris - I can haz Euro spec?
03/14/2014 at 12:30

Ah, that makes far more sense as a question.

Osiris - I can haz Euro spec? > liquid_popcorn
03/14/2014 at 12:33

I don't know if you read the conversation between me and Nibbles, but he knows a guy who's dad had a 1999 Dakota with the 5.9L. Starting to wonder if it was a limited run or something like that.

Zoom > Osiris - I can haz Euro spec?
03/14/2014 at 12:44

The R/T had a 5.9, and Dakota Quads (four doors) were available with it.

Osiris - I can haz Euro spec? > Zoom
03/14/2014 at 12:48

See, that's the funny thing. Mine's a 2 door SLT model with the bench seat in the rear. I've gone to both NADA and KBB to price it up and I can't even do that because there is no SLT model with the 5.9L and 2 doors. It's...interesting albeit a little annoying. It's hard to price a car that either was a limited run and no one remembers it, or never existed as a factory standard.

Nibbles > Zoom
03/14/2014 at 12:58

They were, yes. After 1998 the 5.9 became a regular production option for the Dakotas. However, pairing that block with a manual transmission was seemingly not. The NV3500 was only manufacturer rated for 300 lb-ft, thus was paired with the 5.2. The NV4500 was paired to the 5.9 in the x500 lines, but would require tunnel and firewall modifications to fit in a Dakota. Either it is an engine swap (feasible, as the 5.2 and 5.9 are nearly identical) or somehow a custom order pickup.

Dodge is known for sometimes building those special optioned trucks. My wife had a 1997 Dakota SLT, single cab standard bed 2wd. Under the hood was a 5.2 Mag. When she was hit by a drunk the insurance company could not value the truck properly because, according to Chrysler, the 5.2 was only available in 4WD configurations for MY 1997, yet there are a number of these trucks putting along.

Osiris - I can haz Euro spec? > Nibbles
03/14/2014 at 13:02

That's awesome. So, since the CARFAX didn't list any accidents, I either have a specially requested vehicle or an engine swap. I'm assuming the engine swap is the more likely option.

Tentacle, Dutchman, drives French > HammerheadFistpunch
03/14/2014 at 15:22

Not true anymore. Not since engines have ECUs and knock sensors. Sure, if your engine has a carb and traditional distributor, premium fuel won't help.

BUT... once your engine has an electronic brain and a knock sensor, the game changes. A modern ECU will retard or advance spark timing based on sensing knock. A higher octane fuel will make a difference.

See this Fifth Gear segment:

Even with my old 2001 1.6 liter 4-banger NA engines Euro compact, I could notice a small but significant difference between normal 95 octane and 97/98 octane. And 100 octane (available next door in Germany) is better still. It's not a world of difference, but the engine will be more responsive and will have more mid-range torque because spark timing can be moved closer to TDC.

HammerheadFistpunch > Tentacle, Dutchman, drives French
03/14/2014 at 15:24

Its still the rule