You don’t need to be an expert to realize you need to change your dirt bike gearbox oil.
There’re several tell-tale signs, including a noisy ride, whining and growling sounds, and the most evident one is grinding and shifting trouble.
Unfortunately, a transmission oil change is usually easy to miss because there’re no maintenance schedules for gear oil, unlike the engine oil.
On top of that, it puzzles me that many riders are increasingly getting drawn in by “lifetime fluids,” also known as “fill for life” fluids. It easily appeals to the owner’s desire to minimize maintenance costs.
But in my opinion, that’s crap, and we all know there isn’t magic lifetime fluid.
After all, oils deteriorate in use like anything in life, and gear oils, especially, pick up a lot of debris.
Having replaced the so-called lifetime fill on my Silverado 2 stroke dirt bike, I can confirm that the gear change has drastically improved.
At the time of purchasing my Silverado, it had a full history and was in lovely condition. But the shift from 1st to 2nd gear was obstructive, especially when cold.
I got the mechanic to change to gearbox oil during my routine services, and after that, I’ve not experienced transfer cases so far.
What baffled me most was the state of stuff that came out of my motocross during the replacement. I wished I had done it earlier.
But I’m glad I didn’t have to deal with expensive repairs, rebuild, or replacements.
Now, I know you might be thinking about whether all of this is necessary.
My advice is you need to replace your gearbox oil. It’s the very lifeblood of your gearbox.
And while at it, don’t make the mistake of cheaping out on gear oil replacement.
A high-quality transmission oil will lubricate, cool, and protect your bike’s geared system. It can also suppress the level of noise and move away damaged wear debris from gear contact points.
But with so many transmission oils in the market, choosing the correct oil for your needs can be nerve-wracking.
Fortunately, I’ve done the hard work for you, and in the guide below, I’ll share some of my favorite dirt bike gearbox oils.
Table of Contents
The Best Dirt Bike Gearbox Oils For The Money
#1 Lucas Gear Oil - EDITOR'S CHOICE
Few brands are as premium as Lucas; they’re known for providing great products, and it’s not a surprise they’re always on top of the bunch.
So, when I learned that I needed to run synthetic on my Silverado, I decided to give the Lucas gear oil a try.
It was a great purchase decision because, after extensive research, I found out that it was the same as the Fox Float Fluid, just without the blue additive.
Lucas oil comes at a fraction of the Fox Fluid, and for its price, I get about five bottles for every liter Fox Fluid.
And the best part is I liked the feeling that I’m putting a quality product in my engine. Using Lucas has given me the longevity I needed to capitalize on my investment.
A great benefit with the Lucas Gear oil is that it’s a multi-purpose option, serving different engine lubrication needs.
According to the manufacturer, the oil works well for both the 2-stroke and 4-stroke engines. Above all, it supports most heavy-duty applications and even race cars.
Personally, when I’m not using it on my two-stroke dirt bike engine, I use it for lubricating my dirt bike chain and for general maintenance.
The other draw to this oil was how well it reduced the clunking engine noise.
See, previously, I used Royal Purple oil, and even with its claimed friction reducer, my diff would scream around every corner.
After draining the junk and adding Lucas oil, I couldn’t believe I was tearing through the dirt, and my bike sounded just perfect.
I’m not exaggerating anything, but down the Interstate, I could hear nothing but the wind. It was almost like I was coasting, and honestly, I’ve not experienced anything like this.
On top of that, it even stopped the weird pinging on the hot days and smoothed out the engine more than anything before.
Transmission is also incredible, and it has done away with the clunk that came with engaging the first gear.
And here’s the kicker!
I no longer experience any trouble engaging Neutral. The transmission shifts smoothly, and my ride is effortless.
After several miles of use, I’ve also realized that it has improved my climbing ability. I’m pleased with how it adheres to the existing gear train and pulls itself on the moving parts for more power and strength.
Overall, I can’t complain about the Lucas oil.
It has served me well and upped my performance in numerous ways.
#2 Bel-Ray BT1 Gear Oils – Best for Harley Davidson
I decided to give the Bel-Ray BT1 Gear Oils on the advice of my mechanic.
My Street Glide was having some serious issues, including loud shifts and hard clunks.
Of course, I knew the problem was with the transmission oil, but I was still undecided on what option to choose.
See, I’m a bit conservative when it comes to venturing outside genuine Harley parts and accessories.
But after a suggestion from my mech, I decided to give it a try.
I’m glad I did because this is the only oil you need for Harley transmissions, period.
After trying so many different options, nothing compares to the Bel-Ray BT1 Gear Oils.
It has a smooth shifting, free of the “clunk” that comes with the generic oils.
It’s also among the viscous oils on our list, and this is great for eliminating sliding friction on the moving gear parts.
When in use, my bike shifts like butter with no power loss. Seamless and easy.
My transmissions are quieter than before, but the greatest difference is how smooth the shifts are.
Compared to my previous gear oil, the difference in gear shift is like night and day.
Today, I find more joy riding my Street Harley because of the smooth shift and nice ride.
On top of that, I no longer have to worry much about the gear surfaces breaking or anything.
The anti-friction additives used here shield the sensitive gear components from shock, thanks to the numerous additives.
Along with superior & long-lasting protection, the additives also play an important role in preventing rusting and oxidation of the gear components.
It also means I can use my dirt bike even in a range of temperatures and higher levels without trouble.
Another draw with this oil is that it’s long-lasting and has outlived many of the previous options I’ve had before.
The reason is it has high shear stability, thanks to its dense nature, and so it’ll easily resist the premature oil breakdown or evaporation caused by gear shifting.
It also stays and keeps the engine clean, and during the oil change, you’ll realize that it has a lot less meat on the magnetic drain plug.
Overall, I don’t think there’s any better oil for your Harley Davidson than the Bel-Ray BT1 Gear Oils.
I’ll always use this and would recommend it for your HD dirt bikes.
#3 Red Line V-Twin Transmission Oil - Red Line V-Twin Transmission Oil
I’ve been using the Redline for quite a long time now, and I’m happy with it.
This stuff is great and provides for seamless gear transmission.
And make no mistake, I’m a lubricant nut and often experiment with different oils for my dirt bikes.
I’ve tried Amsoil, Mobil, and other synthetics, but the Red Line makes a huge difference in smooth shifting and noise. This is not to mention all the transmission wear, rusting, and corrosions were arrested.
See, with my previous Amisoil, I used to experience choppy and abrupt wet clutch engagement, especially in hot conditions.
With the Red Line, however, I’ve experienced none of that. My shifting and clutch engagement has been smooth all through.
On top of that, I no longer have to announce my arrival everywhere I go. It’s much quieter than I now even hear the valve train clicking away at highway speeds. At first, it even made me think something else was wrong after the switch.
RedLine offers nice lubrication between the gear teeth and reduces friction on the gears and wet clutches.
See, unlike other oils that are too slippery for wet clutch operation, Red Line is a friction-balanced product. It’s vicious enough to provide less slip and smoother operation and helps apply more power in modified engines.
Plus, the anti-corrosion oil provides ultra-high film strength to coat the gear surfaces. This helps to reduce friction while prolonging the life of the gear. It’ll shield the component from rusting, corrosion, or any other element.
The thick fil coat is also handy at heat dissipation in your gearbox. It works well to help in eliminating the possibility of overheating or anything. So, yes, I can now rack up more miles even in the hot and sunny conditions without worrying too much about my 2-stroke dirt bike blowing out.
A signature benefit of the Red Line oil is the shock-proof features.
It effectively dampens the noise by reducing the shifting clunk and singing. It doesn’t come better than this because it’s primarily used in noisy four-stroke ATVs and motocross bikes.
I also realized the Red Line had a distinctive color, pink.
The added benefit of the pink color is I can immediately diagnose an oil leak and point out whether it’s coming from the tranny or not.
Overall, Red Line is an awesome motocross bikes gear oil.
Yes, it’s expensive but not comparable to most of the oils in the market.
#4 Motul Forcefield Transoil Lubricant – Multi-Purpose Multi-Grade Oil
If you’re looking for nice replacement fluid for your two-stroke dirt bike, give the Motul Transoil Lubricant a try.
I replaced it on my sports bike, and all the gear noise has vanished, and shifting is so much smoother now and with no power loss.
Performance aside, one of the greatest draws to this oil is its versatility.
I mean, there’s literally no engine oil that it can’t work with, from trailers, 2 & 4-stroke engines to scooters and mopeds.
Personally, when I’m not using mine on my 2-stroke engine, I use this motor oil to lube my 2-stroke dirt bike chain and even use it for different activities such as the general maintenance services at home.
And the good thing is whatever purpose you’ll use it for, you’ll always get the same great performance.
It boosts the overall performance of your engine and may be particularly handy in high-stress applications. The oil meets the demands of racing, hill climbing, or high-temperature riding.
Motul oil is a much more high-quality option for your two-stroke dirt bike. You can even tell by letting it run between your fingers because it feels so much better.
What about the riding performance?
On my first drive, I felt the difference. My transmissions were smoother than ever, and I didn’t experience the previous notchiness.
I guess the smooth ride is because of the unique blend of easter components, specific additives, and high shear strength polymers. They are quite handy in helping with the lubricating effect. They also make switching effortless.
Several seasons into using the oil (1000 miles), my ride is still as smooth as when I first replaced the oil.
I’ve not even been locked out at any time in reverse after replacing my oil. I can even downshift into first gear at low speeds in case I decide to abuse the synchros.
The experience is quieter and nicer. I’ve also realized that I gain more speed faster and get into gear faster too.
Meanwhile, I no longer worry about the gear components grinding themselves to death because the oil is vicious. It provides a thick coating over the components, lubricating the gears against friction.
At the same time, the oil can maintain its quality even when subjected to high temperatures.
Long story short, Motul oil seems like a pretty decent option.
It ticks all the boxes, and everything about this gear oil is perfect.
The only knock with Motul is that it has a long list of alkaryl sulphonate ingredients.
This is to mean it can be allergic to some users. So, you need to confirm the ingredient list and see that it won’t affect you in any way.
Otherwise, it’s a great product and would have easily topped our list, save for the allergy part.
#5 Honda Transmission Oil – Best Dirt Bike Oil for Honda Bikes
You’ve a Honda Dirt bike?
If so, nothing beats the Honda Transmission Oil. It works well with Honda CR, TRX models, and CRD.
On top of that, the oil is compatible with different engine oils and will work well with both the 2-stroke and 4-stroke engines.
Performance-wise, the Honda Transmission Oil is a beast.
It’ll level up your performance in many ways.
First, it has high thermal stability.
It means even after use, it retains the same original quality as it was when new. For example, when riding in hot conditions, I don’t have to worry that the oil will transform into foam or anything else, compromising its lubricating abilities.
Thermal stability is also necessary for extending the overall longevity of the oil. While it’ll not last infinitely, it doesn’t break down as easily as other oils do, and this is to mean it’ll keep your engine stay lubricated for long.
Meanwhile, Honda Transmission Oil also stands up to extreme conditions. It will allow your bike engine oil to excel in extreme conditions, including high temperatures and high-pressure conditions, such as when you’re racing or riding up a mountain.
Personally, I ride hard and for long hours, and so far, I’ve not encountered any problem or seen the need for changing the 2-stroke dirt bike oil often.
Another great draw on the Honda Transmission Oil is its incredible shear stability and high film strength.
Combined, these features help to improve the overall durability of your bike’s gear.
See, during riding, the gear components are under extreme pressure and tend to wear from inside.
But the high viscosity of the Honda Transmission Oil ensures everything in your gearbox stays consistent and this helps with slowing down the premature breakdown and reducing drag.
Shifting with the Honda Transmission Oil in between the gear components is also super easy and seamless.
Even when under a load, I don’t experience drag or anything or the clunk noises and screams from the Honda Dirt Bike gearbox.
Special advanced additives help with the overall performance and, more importantly, help reduce slippage between the moving parts and extend the clutch life.
Overall, the Honda Transmission Oil is a nice purchase for Honda users and will go a long way to helping them improve their overall ride performance.
Best Dirt Bike Gearbox Oil Buying Guide
There’re several essential factors to consider when selecting the best dirt bike gearbox oil for your bike.
In the guide below, I’ll share what you should know to ensure you make the right purchase decision.
Everything you Need to Know About Dirt Bike Gearbox Oil
The first thing you need to know about transmission oil is that it’s generally used on 2-stroke engines.
The very design of the 2-stroke dirt bike engine is different from a 4-stroke engine in that the oil needed for the gearbox is different from that of the head.
On the other hand, most of the 4-stroke engines generally use the same oil for all chambers.
However, there’re unique instances in the 4-stroke engines.
Some 4-stroke engines, such as the CRF250, have separate oil chambers and may take on the transmission oil.
But for most cases, the gearbox oil for a dirt bike is used on the 2-stroke engines and not the 4-stroke engines.
Now, with that clarification out of the way, let’s discuss the essential features to consider when selecting a gearbox oil for your dirt bike.
Purchase Decision: Factors to Consider when Selecting the Best Dirt Bike Gearbox Oil
Viscosity is a measure of the resistance of a fluid to change to shape or deform.
In most cases, higher viscosity is usually associated with the level of liquid thickness.
The best transmission oil for a dirt bike should be viscous enough not to evaporate under extreme temperatures and pressure conditions.
Remember, the gearbox oil is subjected to extremely high temps. If it gives in, it loses its viciousness, which means it’ll fail to offer sufficient lubrication or long-lasting protection.
It’s good to consider the type and number of anti-friction special additives in your gearbox oil.
Further additives are the extras that help in boosting the overall performance of your gearbox.
They may also play a big role in improving the chemistry of your oil for more efficacy.
Transmission oils come in different colors.
The choice of colors affects visibility. Bright colors such as red are easy to spot in case of damage.
With time, the color of the oil changes, which makes it quite easy to identify when you need to change the dirt bike oil.
Along with the anti-shear additives, check to see what actual components are included in your oil.
These are what affect the overall performance.
Some of the components you should seek to see in your oil are high shear strength polymers because they affect the overall lubricating performance.
Smell helps riders in identifying when their bike leaks.
Most oils come in a sensational and refreshing mall, making it easy to know when a leakage happens.
Quality is a bit subjective.
But you know a bit about it from reviews.
Check to see that your choice of oil is vicious, has a long life, and has great lubricating effects.
More importantly, ensure that it can stand up to the extreme temperature condition without changing the quality or anything.
The ideal gearbox oil should always keep the moving parts greased.
Long-Lasting Protection Against Elements
Along with the actual lubrication performance, the ideal dirt bike gearbox oil should be resistant to elements.
It should resist oxidation, for example.
Also, it should rust or anything.
Remember the oil attaches to the gear’s surface, and in case it gets compromised, it’ll also affect the overall performance.
Dirt bike oil may contain different chemicals that may be allergic to humans.
For example, some bikers also complain about teary eyes when using certain oils.
So, be sure to check the chemical composition to see there’s nothing allergic to you.
*It’s a good idea to wear protective gloves when changing your transmission oil.
Best Dirt Bike Gearbox Oil Frequently Asked Questions (FAQs)
Q: Do Motorbikes need transmission oil?
A: Yes, high-performance bikes require gearbox oil.
They have engine oil, and therefore, they need lubrication on the gear parts.
Q: Can I substitute my 4-stroke dirt bike oil for a 2-stroke bike?
A: No, I would never advise using a 2-stroke oil on a 4-stroke engine, or vice versa.
See, using a 4-stroke engine can be damaging to your 2-stroke engine.
Q: Is synthetic oil good for my bike?
A: I don’t see any reason why you shouldn’t use it, provided it matches your bike’s specification.
Keep in mind though that synthetic oils aren’t long-lasting.
Their performance is also a bit wanting because they offer less friction; they’re not vicious.
Q: How do I know my bike needs a transmission oil replacement?
A: It’s easy to know because they’re several tell-tale signs.
For example, you might notice the bike producing growling sounds. There’s also difficulty when changing gears.
The engine light may also go dim, and the oil changes colors to grimy black.
Q: Is a 2-stroke engine high maintenance?
A: I don’t think so.
In fact, it’s more simple than the 4-stroke engine.
Plus, it comes cheap.
However, you need frequent replacement of the 2-stroke engine rather than the 4-stroke engine.
Q: Why are 2-stroke bikes louder than the 4-stroke engines?
A: The reason is the 2-strokes fire engine twice and exhausts the system extensively.
Wrap Up: Our Recommendation
Our winner for the best dirt bike gearbox oil is the Lucas Gear Oil.
It’s not hard to see why.
The dirt bike oil comes at a fraction of most premium options, yet it has all it takes to level up your performance.
I’m pleased with its viciousness, and it’s enough to keep your gear components sufficiently lubricated and free from clunk.
It also smoothens the engine performance and keeps everything in pristine conditions and for long.
I would highly recommend.