Maxima Fork Oil for Vintage Honda Motorcycles
Fork oil is the fluid your front suspension pushes through to control how it compresses and rebounds. As it ages it breaks down and foams, your damping fades, and the front end starts to feel harsh and uncontrolled. This is fresh Maxima fork oil in 10WT and 15WT, the grades that cover the whole vintage Honda range.
Why You Need This
A fork-oil change is one of the cheapest, biggest improvements you can make to how an old Honda rides. Old oil loses its damping and lets the fork foam, so the front end packs down over bumps and dives under braking. Fresh oil brings the damping back. Maxima’s Lubricinol additive package fights that foaming and conditions the fork seals as you ride, so the seals stay supple and leak later.
About Maxima Fork Oil
- Mineral-based fork oil built for the standard telescopic forks on vintage Honda front ends
- Lubricinol-fortified additive system — minimizes foaming and conditions the fork seals
- Offered in two weights, 10WT and 15WT (see below to choose)
- 1 Liter (33.8 oz) bottle — enough oil to do two complete sets of forks
Which Weight: 10WT or 15WT?
From the factory these forks were filled with ATF — roughly a 5-weight oil. Maxima’s 10WT and 15WT are a step up from there, and you pick between them by rider weight and how you ride:
- 10WT — the right choice for most riders under about 200 lb, on normal roads.
- 15WT — more damping for heavier riders, or for rougher roads where you want a firmer, more controlled front end.
Both weights fit every model below — the weight is about feel, not fitment.
Specifications
| Spec | Detail |
|---|
| Type | Mineral-based motorcycle fork oil (Lubricinol anti-foam additive) |
| Weights | 10WT or 15WT (choose by rider weight) |
| Volume | 1 Liter (33.8 oz) — does two sets of forks |
| Factory Fill | Honda originally specified ATF (about a 5-weight) |
| Fits Models | Vintage Honda telescopic forks — CT90, CB100/CL100/SL100, CB125/CL125/SL125, CB175/CL175/SL175, CB200/CL200, CB350/CL350/SL350, CB360/CL360/CJ360, CB450/CL450/CB500T, CB500K/CB550K/CB550F, CB750 |
| Sold As | Individually (1 Liter bottle) |
How Much Fork Oil Does My Bike Need?
These are approximate amounts per fork leg for an oil change. Always measure the exact volume with a graduated cylinder — an under- or over-filled fork damps poorly. On several models the amount changed across the years as the fork design changed, so match your exact variant:
| Model | Per Fork Leg (approx.) |
|---|
| CT90 / Trail 90 | 120–140 cc |
| CB175 / CL175 | 135–145 cc |
| SL175 | 175–185 cc |
| CB200 / CL200 | 115–130 cc |
| CB350 / CL350 — early (external spring) | ~200 cc |
| CB350 / CL350 — late (internal spring) | 135–140 cc |
| SL350 | 180–190 cc |
| CB360 / CL360 / CJ360 | 135–140 cc |
| CB450 / CL450 (K0–K2, 1965–69) | ~290 cc |
| CB450 / CL450 (K3–K4, 1970–71) | ~225 cc |
| CB450 / CL450 (K5, 1972) | ~160 cc |
| CB450 (K6–K7, 1973–74) | ~140 cc |
| CB500T | ~140 cc |
| CB500K (CB500 Four) | ~160 cc |
| CB550K / CB550F | 165–170 cc (oil change) · 185–190 cc (full rebuild) |
The early CB350/CL350 forks carry the spring outside the tube; the later ones moved it inside, and the fill amount dropped a lot — so confirm which you have before you measure. (Also fits the CB100/CL100/SL100, CB125/CL125/SL125 singles, and CB750 — we don’t publish a per-leg figure for those yet, so measure your fill carefully.)
Installation
Difficulty: Beginner
On most of these bikes you can change the oil with the forks on the bike:
- Loosen the fork top cap before you lift the wheel (it’s easier with the fork compressed).
- Pull the drain screw at the bottom of the fork leg and let it drain, then work the fork up and down to pump out the rest.
- Reinstall the drain screw, then pour in your measured amount of fresh oil through the top.
- Reinstall the top cap, and repeat on the other leg.
We walk through the whole job in our fork-oil-change video:
Frequently Asked Questions
Should I use 10WT or 15WT?
Pick by rider weight and roads, not by model. 10WT suits most riders under about 200 lb on normal pavement; 15WT gives a firmer, better-controlled front end for heavier riders or rougher roads. Both fit every model in the chart.
How much fork oil does my bike take?
See the per-leg chart above — it ranges from about 115 cc on a CB200 up to ~290 cc on an early CB450. Several models changed across the years (the CB350 and CB450 especially), so match your exact variant and measure with a graduated cylinder.
Is this the same as ATF? What did Honda spec?
From the factory these forks ran ATF, which is roughly a 5-weight oil. This Maxima oil is a purpose-made fork oil in heavier 10WT and 15WT grades, with an anti-foam additive package — a step up from plain ATF for these old forks.
How often should I change it?
Every 10–12 months for a regularly ridden bike. If your front end feels harsh, bouncy, or is leaking, it’s past due.
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Last updated: June 2026
