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Ari’s answers: All about oil

May 19, 2020

Oil can be a slippery subject. Many of the longest and most contentious threads on online motorcycle forums started with a simple question about which oil to use. So let's cut through the noise and get to your questions.

Editor's note: Ari's Instagram inbox is often full of technical questions, and he replies to (almost) all of them. We publish a few of the answers here so others can benefit from the info. Got a question you'd like answered? Leave it in the comments section below or message him on Instagram at @arihenning211.

To keep your bike’s engine happy, avoid oils labeled energy or resource conserving (API symbol at left) and select a lube labeled MA or MA2 (JASO insignia at right). Photo by Spenser Robert.

Would it be okay to use car oil in a motorcycle, and if not, why? — @jake_scott15

The short answer is no, and that’s because auto oil might cause your moto clutch to slip. 

Many of today’s auto oils contain soluble molybdenum compounds and other friction modifiers. These compounds chemically adhere to an engine’s internal surfaces to help reduce friction and improve efficiency — by up to three percent, according to API (American Petroleum Institute) criteria and testing. 

While reduced friction is great for automotive fuel mileage, it’s not ideal for your bike’s clutch plates, which rely on a certain amount of friction to do their job. So to avoid trouble, you’ll want to avoid using auto oil in your motorcycle’s engine. Friction-modified auto oils will have an “energy conserving” or “resource conserving” designation in the circular API service symbol on the back of the bottle (see photo above), so they’re fairly easy to identify. 

Motorcycle oil, which is specifically formulated to work with wet clutches, is easy to spot as well. Look for the JASO (Japanese Automotive Standards Organization) MA specification, which is usually listed on the front of the bottle. There are numerous other API and JASO standards that apply to motorcycle oils, so it’s best to review your owner’s manual to see exactly what the manufacturer recommends.

And since it’s a common followup question, no, you don’t have to use Yamalube in your Yamaha or Pro Honda lube in your Honda, even if that’s what the manual recommends. As long as you’re sticking to the required API and JASO service grades and specifications, the brand doesn’t matter. 

Exposure to moisture and combustion byproducts means that oil ages with time, as well as mileage. That's why there are two criteria listed in your manual for when to change it. RevZilla photo.

I recently bought a used 2018 Bonneville. It had 4,000 miles on it when I put it away for winter storage. I just pulled it out and am wondering if there’s any concern about the oil that’s been in there for an extended period of time. Should I be doing an oil change even though I’m far from the recommended interval? — @nocturnalescapist


Ha, I wanted to leave it at that but every answer deserves an explanation, especially this one. 

Oil is a complicated concoction and contains a lot of specialized additives in addition to the base stock. In fact, up to 30 percent of each bottle of motor oil is stuff like anti-foaming agents, antioxidants, demulsifying agents, the aforementioned friction modifiers, and a package of chemicals known as the TBN, or Total Base Number. 

The TBN fights acid formation, which can occur when sulphur in the gas and oil base stock combines with oxygen and hydrogen present in the crankcase (most often in the form of moisture). The process happens more rapidly when the engine is running, but still occurs when the bike is parked, which means the TBN gets depleted over time regardless. 

That’s one reason your owner’s manual lists a mileage interval and a month interval for oil changes, because oil begins to degrade as soon as you pour it out of the bottle. 

Oil flowing through the holes in this crude device is what provides damping in a damping-rod fork. The larger hole at left is for compression, the smaller hole at right is for rebound. Photo by Ari Henning.

What are some affordable ways to make a fork firmer? It’s a weak point on my MT-07. I’ve heard of using thicker fork oil. Anything else like this? — @thomasthetrol

Two common “fixes” for flaccid damping-rod forks is to add spring preload and/or swap out the fork oil for a heavier weight fluid. 

I put “fixes” in quotes because both mods are Band-Aids that may help with the primary problem, but will introduce other issues. 

Adding more preload to springs that are too soft for your weight will help reduce bottoming and keep the suspension higher in the stroke while you’re riding, but it will throw your sag figures out of whack and inhibit compliance over small bumps since the spring requires so much initial force to begin moving. 

Likewise, putting heavier oil in the fork may improve slow-speed compression and rebound damping for better support on the brakes and while cornering, but you’ll likely experience too much high-speed compression damping, which will manifest itself as a harsh feeling over hard-edged bumps. 

If you can pry your wallet open and shell out $130 for a set of performance (read: straight rate) springs, that'll properly fix at least one aspect of your FZ's front end. I'm fond of Race Tech products, and they have an excellent spring-rate calculator on their website to help you figure out which coils you need. The same calculator also has recommendations for oil weight, oil height, and various other setup parameters. It's a super handy resource. 

Springs still only address half of the problem though.

To really fix any damping-rod fork, you’re going to need to spend some money. Two popular solutions are Race Tech’s Gold Valve Emulators (along with a set of springs) or a cartridge kit like those offered by Andreani. Of the two, the cartridges are more expensive (about $600 compared to approximately $300, plus labor if you opt to pay someone to do the work), but provide a more comprehensive fix that leaves you with external spring preload, compression and rebound damping adjustments, regardless of what adjustments your OE fork offers. With the Gold Valve kit, you’ll need to retrieve the emulator from the fork and/or change the fork oil to fine-tune the damping, and the installation process is a bit more involved. 

As with most things, you get what you pay for when it comes to suspension mods. Free or cheap fixes may sound appealing, but in my opinion it’s worth investing in improving the suspension, since it will improve all aspects of the bike’s functionality.