Primus Omnifuel 2 Review

Base stats:
– BTU:  10,500 (White gas)
– Weight:  12.3 oz min, 15.9 oz packed
– Stove comparison review

The skinny: An evolution of the original Omnifuel, more refined, more precision focused, with a detail oriented addition of features, while still remaining rugged and reliable.

Caution:  There was an issue with an earlier version of the OmniFuel 2 stove.  See photos in addendum A at the end of this review.   (damaged omnifuel photos courtesy of BC).  

NOTE:  This appears to have been fixed with the current version.  See comment from Scott Boyce on Feb 22nd, 2017 in the comments section.

It’s lighter, has made improvements on minor issues with the original, and kept all the things great about the original, except in one minor aspect: that lightness comes with just a little shaving of the thickness of the pot stand/legs.

It is still very rugged. Certainly tougher than the OmniLite, but the pot stand does have just a little more torsional give than the pot stand legs of the original.

Starting at the pump, nothing has changed. The pump is the same awesome ergopump used in all other Primus liquid fuel stoves and I’m deeply gratified for this. The pump line and fuel intake are both still mostly metal, the pump handle has the same smooth action, they have kept throttles off the pump (great to avoid worrying about it opening while in the pack), and the screw threads are angled to ensure the fuel intake goes to the inside wall of the bottle.

(Left to right:  Omnifuel, Omnifuel II, Omnilite)

Next up is the fuel line. Again here, it appears as though nothing has changed. The secondary throttle and fuel rod is also identical. The fuel rod is connected directly to the firewall/fire ring/flame spreader. And that wall seems about the same as the Original, with the same heat collecting base.

The pot stand/legs and the outer heat shield are very new.

Omnifuel II on left, Omnifuel on right, notice the larger gap in the original Omnifuel’s heat shield cutout for the fuel rod.

The heat shield seems now slightly thinner, and has form fitting cutouts for the fuel rod, so there isn’t any movement. This is a real improvement. The previous heat shield had a larger cutout allowing the firewall and fuel rod to jiggle a bit. Over time, this loosens the base screw. Not a big deal but it was necessary to tighten that base screw pretty regularly. The form fitting cutout means the fuel rod cannot really move so there is no jiggling over time, which in turn keeps the base screw from loosening.

Original Omnifuel

The original also uses a key ring to keep the flame spreader from getting lost. The tiny annoyance was that when removing flame spreader, it hooked in a little making it a bit finnicky to remove it.most folks just bent out the hooks a bit to make the flame spreader easier to remove.

Omnifuel II (flame spreader)

The new Omnifuel uses a coil spring to hold the flame spreader taught. Two of the flame spreader hooks bend sharply hooking onto the firewall very well. The third hook is actually angled wide, away from the firewall wall and pulled tight with the coiled spring to secure the flame spreader in place. This is a very minor change but quite welcome.

NOTE:   First version of OmniFuel 2 stove had a design flaw with the splash guard/flame spreader pictured above.  See Addendum A at the end of this review.  (Photos of damaged omnifuel courtesy of BC).  This appears to have been fixed with an updated version of the OmniFuel 2 by loosening the tension of the spring. (see comment from Scott Boyce on Feb 22nd 2017, in the comments section below)

The heat shield also has an imprint of the bolt descriptions in case you forget what each jet bolt (nozzle, nipple) is for. They also added dots to make the jet bolts easier to identify. One dot for LPG, two dots for white gas/unleaded, and three dots for kerosene, diesel, jet fuel.

The legs have changed significantly. The result of the change is roughly the same diameter when opened up (compared to the original),

but when folded, the overall length seems a little shorter and when opened it is just a wee bit taller.

Original Omnifuel on left, Omnifuel II on right

As mentioned before, the pot stand legs are just a hair thinner than the previous version. This makes them significantly lighter but also a wee bit more bendy. Still significantly thicker than the Omnilite pot stand legs.

The way the legs open and close has also been changed.

Original Omnifuel

The original omnifuel has two pivot screws, one for two of the legs, and a second pivot screw for the third leg.

The Onnifuel II pivots around the central base screw, similarly to the Omnilite. Additionally, the “lock open” mechanism has been changed.

It’s a more secure spring lock mechanism, that keeps all three legs locked innplace much more securely.

Unlocking now requires pushing in the spring lock to pivot the legs closed.

Is this different? Certainly. Is it better? Time will tell. I can imagine sand getting into the mechanism and causing more annoyance but in clean environments, I’m sure it would be fine.

The leg also now holds the spare jet bolts (a.k.a. nozzle, nipple).  Presumably so you don’t lose them, though, they don’t screw in particularly tight.

The photo above shows a separately purchased kit, but the tool you see in this kit is the same as the one that comes with the Omnifuel II.  The grease tube is also the same.  The multi-tool is the same as the Omnifuel and Omnilite.  Nothing new.

In terms of function, they are identical. Stoves based on fuel rod and firewall heat concentrators (like the Omnifuel, Onnilite, Nova, and Polaris Optifuel), generally seem to take just a shade longer to prime than generator coil based liquid fuel stoves, and the Omnifuel II seems similar. I tried white gas, and as is typical, with a very slight breeze, it took over a minute to prime the stove. I could be wrong, but it does feel that way. Despite that, I tend to prefer these types of stoves over generator coils, which are made from soft metals, making me nervous for failures in the field.

Once the flame gets going, it is nice and blue, but the flame spreads much wider than original Omnifuel, and does have orang’ish tips especially at full blast.

Having said that, it’s reasonable to assume the fuel efficiency should be roughly the same as the original Omnifuel, as the btu measure and the jet bolt gauges are the same. I haven’t done a carefully measured fuel bottle test but it definitely sips fuel faster than the OmniLite and seems about the same as the original Omnifuel in about an hour’s testing of the stoves side by side.

The precision simmering capability hasn’t changed much, it’s still amazing. This second generation is, as is the first generation, a stove designed for real cooking, not just quick boils.

Incidentally, here it is with the Silent burner (meant for the original Omnifuel.  Still works, though not quite as effectively as with the original)

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So what’s a good cook set combination for this stove?

The Omnifuel II fits inside the Optimus HE Weekend.  While it fits inside without an issue, the two aren’t a good match.  the Optimus HE Weekend is good for very simple meals, and frankly the Omnifuel is designed for wider pots and pans and more involved cooking.  They work together fine, but the Omnilite and Edelrid Hexon are better fits for this pot.

The Snow Peak Trek Combo works will with this stove, but again, it’s almost too much stove for this pot set.

The Snow Peak Multi-Compact cookset is a challenge for most liquid fuels stoves, and it’s no different here.  The Omnifuel II doesn’t fit inside the smaller pot, but it does, sort of but not quite, fit inside the large one.  If you planned on camping with just one pot and pan set, and left the smaller one at home, this could work.  I’m not a huge fan of the form factor of the Multi-Compact, and believe in a lower and wider pot, but this is starting to get there.

The Omnifuel II doesn’t fit inside the Toaks 1300ml pot, but it fits inside the 1600ml pot.  One pot and pan is just fine by me, so leaving the 1300 behind and just bringing the 1600 would work well for me.  Now we’re starting to get into pots designed for more cooking.  the pan is also pretty large, so it makes sense to do simmer level cooking.

One of my favorite pots is the MSR Alpine Stowaway 1.1L and 1.6L. They are both low and wide pots. The lids are raised, not flat like some camping pots, and those raised lids add just enough height internally for the Omnifuel and Omnifuel II to fit inside.  The center image shows the Omnifuel II in the 1.1L pot.  The 1.6L pot has plenty of room to spare.  On either side are photos showing the respective pots on the Omnifuel.

The only problem with this setup is that if you go this route, all you have is one pot to work with.  There’s no pan for a lid, and you’d have to clean it if you wanted to boil up some water before cleaning the pot after use.

So….with most other pot and pan sets, I would bring just a plastic thermal cup, but when bringing the Alpine Stowaway, I also bring the GSI Halulite, because you can boil water right in the GSI Halulite, and then slip it into the cozy sleeve, add the silicone top, and have a nice warm beverage without burning your hands or worrying that the drink would cool too fast.

The ultimate setup for the Omnifuel II is undoubtedly the Optimus HE Cook set.  This set has the pan, pot with heat exchanger, pot with non-stick coating, and a warming cozy.  It cooks for three people easy, and four if they are reasonably light eaters.  the important thing is to keep the stove well wrapped to avoid scratching the non-stick coated pan.  If planning a trip for 3-4 people, I’d probably bring this setup, and have someone else carry the food.

For the Optimus HE cook set, I use the heat-exchanger pot only for boiling water, nothing else. I use the non-stick pot for simmering and cooking, and the pan for frying.

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So, in the end, how does this compare to other stoves?

Good question. I don’t know yet.

The answer will come as it always does: On my next backpacking trip. What will I instinctively grab? Will it be the Omnifuel II? If I plan to cook on the trail, probably. We’ll see.

Generally, I’ve leaned towards the original Omnifuel or the Polaris Optifuel when wanting something to depend on, The MSR XGK when wanted something that will just work, every time without fail (with a spare pump because the MSR pumps are fragile), the Whisperlite when I plan on using dirty fuels (basically an XGK that is a tad easier to sort of “simmer” with a little finagling), the Omnilite when wanting to make the fuel stretch as much as possible (the Omnilite is the endurance runner of liquid fuel stoves), the JetBoil when going as light as possible, and a Trangia based setup when going for just an overnighter (fuel gulper, but quiet, easy, and environmentally safe).

But more and more, I think I might lean towards the Omnifuel 2. It’s lighter than the Omnifuel, can simmer extremely well, has some great features, and I’ll worry less about losing the jet bolts.

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Other reviews around the web:

• http://thenextchallenge.org/liquid-multi-fuel-stoves/#omnifuel
• http://classiccampstoves.com/threads/primus-omnifuel-2.30496/
• http://www.mec.ca/product/5043-078/primus-omnifuel-ii-stove/
• http://expeditionportal.com/field-tested-primus-omnifuel-stove/

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COOKING TEST:

Just for fun (I don’t usually do this in reviews), I figured I’d show off the simmering prowess of this stove.

The Omnilite, Omnifuel, and Omnifuel II are all incredible simmering stoves, which makes them ideal for non-stick coated pots and pans.

To show this off, here’s a test noodle curry, with just four core components:

• Curry concentrate
• Water
• Bacon
• Onion

My goal in this test was to minimize dirty dishes, keeping things as clean as possible.

Also, while this is no where near ultralight backpacking…and is more like super heavy backpacking, I still wanted to use just the gear that I’ve taken on backpacking trips before, so here’s what I used:

• GSI macro table (Yep, super heavy table for backpacking, but fits nicely in the Tatonka Lastenkraxe, and I take it on Emigrant Wilderness weekend trips fairly often….crazy, I know).
• Optimus HE Cook Set.  While pretty large, it comes often on weekend trips as there are usually 3-4 people in my group.
• Liquid fuel stove (in this case, the Primus Omnifuel II, but could be any)
• Windscreen 9.5″.  This goes on every backpacking trip, regardless of stove.
• GSI kitchen cook kit.  This has most of the tools and condiments that I need, and works well with non-stick coated cook sets.  Best of all, it has plastic tongs.
• Kuhl silicone pot gripper.  The Optimus HE cook set comes with a pot gripper, and it does have some silicone dots to help mitigate scratching non-stick cookware, but if you’re clutsy like, those dots aren’t enough.  The Kuhl silicone pot gripper is full sized silicone.  While it’s ridiculously large for backpacking, this is a must have in my book if you use non-stick coated cookware.
• folding water bucket.
• rags
• tiny steel knife (could have been the leatherman)

So here goes:

Starting with cutting up the onion and bacon.

Prime the stove:

First up, cook the bacon in the frying pan.  Keep the flame nice and low to keep anything from burning.  As the oil builds, pour the excess into the non-stick sauce pan with the chopped onions.

Oh….time for a break.  Boil up some water for a little instant coffee to keep warm.

Next up, fry up the onions with the oil from the bacon.  As with the bacon, keep simmering at a very low heat, this keeps food from burning into the non-stick coating.  Takes longer to cook, but well worth it to make the non-stick coating last for as many uses as possible.

Then, get the noodles ready.
and then get the curry concentrate going in water.

After that, throw it all together.

And tadaaaaaa!  noodle curry (^-^).
Probably  would have been better with cut up carrots and potatoes, or maybe some celery, but still plenty good.

Okay, the Snoopy bowl and metal silverware isn’t backpacking gear, but, other than that, pretty good little experiment.

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ADDENDUM:  DESIGN FLAW WITH FIRST VERSION OF OmniFuel 2.

NOTE:  This seems to have been fixed with latest version of OmniFuel 2 by decreasing the tension of the spring.

If you look in the comments section, reader BC has been kind enough to send photos of a design flaw he discovered.  This design flaw escaped my notice as, apart from initial testing, all my stove usage utilized the QuietStove stove silencer/muter.

The design flaw exists because of the splash guard.  In the previous generation splash guard, the three tines all applied the same level of pressure to the rim of the copper bell.

This capping method makes the splashguard difficult to remove for maintenance.

The Omnifuel 2 looked to resolve this through a unique spring system, where two of the tines hook on the copper bell, and the third tine is pulled away through a spring.

Under normal operation, as the stove heats the copper bell, and the metal softens, the bell rim begins to warp towards that third tine.

While a little bit of warping is normal, this unique setup causes the warping to become excessive and eventually unusable.

With BC’s permission, I’m including the photos here in this review: