Penrite's MC-4ST range has a lot of bottles on the shelf: mineral, semi synthetic, full synthetic, "100% PAO Ester", V-Twin, HD. If you just want to know which one to put in your bike, this guide is for you.
Step 1: Use a motorcycle oil, not a car oil
Most four-stroke bikes run the clutch in the same oil as the engine (a "wet clutch"). Many modern car oils contain friction modifiers to save fuel. In a bike, those can make the clutch slip. Motorcycle oils like MC-4ST are made to work with wet clutches. If your bike's manual quotes a JASO MA or MA2 rating, that's the wet-clutch standard to look for on the bottle.
Step 2: Match the viscosity in your manual
The numbers (10W-40, 15W-50 and so on) are the viscosity. The first number is how the oil flows cold. The second is how thick it stays at operating temperature. Use what your manufacturer recommends. In Queensland and most of Australia, the hot-weather end matters more than cold starts. Many owners in hot climates, or on bikes that work hard, use the thicker option where the manual allows a range.
Step 3: Pick the base oil
| MC-4ST type | Good for |
|---|---|
| Mineral (15W-50, 20W-50) | Older and air-cooled bikes, farm and trail bikes, frequent oil changes on a budget |
| HD SAE 50 Mineral | Older engines that specify a straight 50-grade oil |
| Semi Synthetic (10W-30, 10W-40, 10W-50, 15W-50) | Everyday road bikes and commuters, a step up in protection without full synthetic prices |
| Full Synthetic 10W-40 | Modern road bikes, adventure bikes and dirt bikes. Our most popular all-rounder. |
| 100% PAO Ester (10W-30, 10W-40, 10W-50, 10W-60, 15W-50) | High-revving sports bikes, track days, hot climates and hard-worked engines where you want the most stable oil |
| V-Twin 20W-50 100% PAO Ester | Big air-cooled V-twins like Harley-Davidson, which run hot |
What does "100% PAO Ester" mean?
PAO (polyalphaolefin) and esters are the premium synthetic base oils. PAO stays stable at high temperature and resists breaking down. Esters cling to metal surfaces, so there's protection on start-up. A 100% PAO and ester oil costs more, but it holds its viscosity longer under heat and high revs. That's why it's the pick for sports bikes and air-cooled engines in summer.
Quick picks
- Modern road or adventure bike, not sure what to get: MC-4ST 10W-40 Full Synthetic
- Harley or other big V-twin: MC-4ST 20W-50 V-Twin 100% PAO Ester
- Sports bike, track days, or a manual that calls for a thicker oil: MC-4ST 10W-60 100% PAO Ester
- Older air-cooled bike or farm bike: MC-4ST 15W-50 or 20W-50 Mineral
How much and how often?
Your manual gives the oil capacity (with and without a filter change) and the service interval. Most bikes take somewhere between 1 and 4 litres, so a 4L bottle usually covers a change with some left to top up. If you run several bikes or do your own servicing, the 20L packs work out much cheaper per litre. Change the oil filter every time if you can, and check the level regularly between services. Air-cooled engines in particular can use a bit.
See the full Penrite range or all motorcycle oils. If you'd like a second opinion on your bike, call us on (07) 3340 4392.