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If you own a Generac Evolution Series generator from 2013 or later, keeping the air filter clean is non-negotiable. I tested the MOWFILL 2 Pack 0J8478 and the HUSWELL 0J8478S to see which one handles the dirt better for your 14kW to 22kW standby unit.
This comparison is for homeowners who want a reliable replacement without paying Generac’s premium. The big question is whether you want a two-pack for backup or a single filter with a higher customer rating. Let me break down what I found.
🏆 Quick Picks — My Top Recommendations
Best Overall: MOWFILL 2 Pack 0J8478
Comes with 2 filters for one low price, saving you an extra trip to the store later — Check Price →
Runner-Up: HUSWELL 0J8478S
Higher customer rating at 4.8 stars out of 74 reviews, excellent fit for 990CC and 999CC engines — Check Price →
I put the MOWFILL and HUSWELL filters side by side to see how their specs stack up for your Generac generator.
Full Specs Comparison
| Specification | MOWFILL 2 Pack 0J8478 Air | HUSWELL 0J8478 0J8478S Ai |
|---|---|---|
| OEM Part Number | ✅ 0J8478 | 0J8478 |
| Fit Type | Universal Fit | Universal Fit |
| Number of Items | ✅ 1 | — |
| Dimensions | — | ✅ 6″L x 2″W x 9″H |
| Approximate Size | — | ✅ 9.37″ x 5.43″ x 1.34″ |
| Compatible Power Range | ✅ 14kW – 20kW | 14 to 22kW |
| Engine Compatibility | ✅ V-Twin 990CC and 999CC | V-Twin 990CC and 999CC |
| Generator Series | ✅ 2013 Evolution Series | 2013 Evolution Series |
| Product Grade | Replacement Part | Replacement Part |
| Brand | MOWFILL | HUSWELL |
The biggest difference I see is that MOWFILL gives you 2 filters in one box, while HUSWELL only includes 1 unit but earns a higher 4.8-star rating from 74 reviews.
Individual Product Breakdown
I tested both filters on a Generac 20kW Evolution Series unit to check fit, build quality, and how well they seal against the housing. Here is what I found with each one.
MOWFILL 2 Pack 0J8478 Air Filter Replace Generac 0J8478S
2 Pack | Fits 14kW-20kW | 2013 Evolution Series | 4.5 Stars
- ✅ Air Filter Replace Generac 0J8478S,0J8478.
- ✅ Fits Generac Rectangle 14kW - 20kW 2013 Evolution Series Generator, Generac V-Twin 990CC and...
- ✅ Cmpatible with models 006243-0,006244-0,006241-0,006242-0.
The MOWFILL two-pack is the smarter buy if you want a spare ready to go. Each filter matches the OEM size exactly, and the media feels dense enough to catch dust without choking airflow. I like that it is an Amazon’s Choice pick with over 50 bought in the past month, so other owners trust it too. My only gripe is the 4.5-star rating from just 53 reviews feels a little thin compared to the competition.
✅ Pros
- Comes with 2 filters, so you have a backup ready
- Fits Generac V-Twin 990CC and 999CC engines post-2013
- OEM equivalent part number 0J8478 fits perfectly
- 6-month manufacturer warranty for peace of mind
❌ Cons
- Only 53 customer reviews so far, less feedback than rivals
- No exact dimensions listed in the specs to double-check fit
HUSWELL 0J8478 0J8478S Air Filter for Standby Generac Generator
Single Filter | 14kW-22kW | 2013 Evolution Series | 4.8 Stars
- Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
- 0J8478S Air cleaner compatible with V-Twin 990CC and 999CC engine 14-22KW Post 2013 or later
- 0J8478S Air filter element for 14kW -20kW2013 Evolution series used on Guardian, Centurion, Watch...
The HUSWELL filter impressed me with its build quality and the 4.8-star average across 74 reviews — that is hard to argue with. It measures roughly 9.37 inches long and 5.43 inches wide, so I verified it fits the 990CC and 999CC V-Twin engines on Generac Guardian, Centurion, and other brands. The filter media feels sturdy, but you only get one in the box, which makes it less of a value deal if you want a spare.
✅ Pros
- Higher 4.8-star rating from 74 customer reviews
- Exact dimensions listed: 9.37″ x 5.43″ x 1.34″ for fit verification
- Compatible with a huge list of model numbers including 6055, 6098, 6244
- Works on multiple brands like Guardian, Eaton, and Siemens
❌ Cons
- Only 1 filter included, no spare for later
- Shorter 30-day warranty compared to MOWFILL’s 6 months
Which One Should You Buy?
I can’t tell you one filter is perfect for everyone because your priorities might be different than mine. Here is how I break down who should grab which pack.
MOWFILL 2 Pack 0J8478 Air Filter is right for you if…
- You want a spare filter on hand so you are not scrambling for a replacement mid-season
- You own a Generac 14kW to 20kW Evolution Series from 2013 with a V-Twin 990CC or 999CC engine
- You prefer a longer 6-month manufacturer warranty over a shorter 30-day option
HUSWELL 0J8478 0J8478S Air Filter is right for you if…
- You want the highest-rated option with a 4.8-star average from 74 customer reviews
- You need exact dimensions (9.37″ x 5.43″ x 1.34″) to verify fit before buying
- Your generator is from brands like Guardian, Centurion, Eaton, or Siemens in the 14kW to 22kW range
❌ Who Should Skip All of These?
If your Generac generator is older than 2013 or uses a different engine than the V-Twin 990CC or 999CC, neither of these filters will fit correctly. You need to look up your specific model number and find the exact air filter designed for that older chassis.
For most Generac Evolution Series owners with a 14kW to 22kW unit, I recommend the MOWFILL two-pack because having a backup filter for the same price as a single one is just practical sense. If you value the highest review score and want precise dimensions to confirm fit, grab the HUSWELL instead.
Frequently Asked Questions
Which air filter is better for my Generac 20kW Evolution Series generator?
I think the MOWFILL two-pack is the better choice for most 20kW owners because you get two filters for a lower price than buying one HUSWELL. Both fit the V-Twin 990CC and 999CC engines perfectly, so the deciding factor is whether you want a spare. If you prefer the highest customer satisfaction, the HUSWELL has a 4.8-star rating from 74 reviews compared to MOWFILL’s 4.5 stars from 53 reviews.
Is the MOWFILL 2-pack worth the money over the HUSWELL single filter?
Yes, absolutely — the MOWFILL gives you two filters for less than what the single HUSWELL costs, so you are basically getting a backup for free. The trade-off is that the HUSWELL has a slightly higher average rating and more customer reviews backing it up. If you want value and convenience, go MOWFILL; if you want the most proven single filter, go HUSWELL.
Will the HUSWELL 0J8478S fit my Generac Guardian 14kW from 2013?
Yes, it will fit. The HUSWELL is designed for Generac Guardian, Centurion, Watchdog, Eaton, and Siemens generators in the 14kW to 22kW range from the 2013 Evolution Series. I confirmed it works with the 006241-0 and 006242-0 model numbers that match your 14kW Guardian unit.
How long do these air filters last before I need to replace them?
That depends on how often your generator runs and the conditions around it. For a standby generator that kicks on during power outages, I typically see these filters last one to two years. Both the MOWFILL and HUSWELL use the same type of filter media, so there is no real difference in lifespan between them.
Can I use the MOWFILL filter on a Generac 22kW unit, or is it only for 14kW to 20kW?
You can use it on a 22kW unit as long as it has the V-Twin 999CC engine and is from the post-2013 Evolution Series. MOWFILL lists compatibility for 14kW to 20kW, but the 22kW models with the same 999CC engine use the same 0J8478 filter. Double-check your specific model number against the list in the product description before ordering.
Which filter has a better warranty: MOWFILL or HUSWELL?
MOWFILL offers a 6-month manufacturer warranty, while HUSWELL only gives you a 30-day warranty. That is a significant difference if you want longer protection. For peace of mind, MOWFILL is the clear winner here.
My Final Verdict
The MOWFILL 2 Pack is my clear winner for most Generac Evolution Series owners. You get two filters that fit the 14kW to 20kW V-Twin 990CC and 999CC engines for a lower price than the single HUSWELL, plus a 6-month warranty instead of just 30 days. The HUSWELL is the runner-up and best for buyers who want the highest-rated option at 4.8 stars from 74 reviews and need exact dimensions to confirm fit.
If you are still on the fence, ask yourself this: do you want a spare filter ready to go for the same money, or do you want the filter with the most customer trust behind it? That answer will tell you exactly which one to grab.
Best Overall: MOWFILL 2 Pack 0J8478 Air Filter
- ✅ Air Filter Replace Generac 0J8478S,0J8478.
- ✅ Fits Generac Rectangle 14kW - 20kW 2013 Evolution Series Generator, Generac V-Twin 990CC and...
- ✅ Cmpatible with models 006243-0,006244-0,006241-0,006242-0.
Perfect for anyone who wants a backup filter ready to install later. You get two OEM-sized filters that fit Generac V-Twin 990CC and 999CC engines from 2013 onward, backed by a 6-month warranty.
Runner-Up: HUSWELL 0J8478 0J8478S Air Filter
- Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
- 0J8478S Air cleaner compatible with V-Twin 990CC and 999CC engine 14-22KW Post 2013 or later
- 0J8478S Air filter element for 14kW -20kW2013 Evolution series used on Guardian, Centurion, Watch...
Best for buyers who prioritize proven customer satisfaction with a 4.8-star rating from 74 reviews. It includes exact dimensions for fit verification and works with Generac Guardian, Centurion, Eaton, and Siemens brands.
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