How do you really know what you're getting when you screw on a new oil filter? That little canister has a big job to do considering it's trying to protect your several thousand dollar engine.
For those lucky enough to have a cartridge-style filter, most of these questions won't apply. You can see every part of the new filter element, you can eyeball all the components on the engine. You can clean out the housing to your own impeccable tolerances. You fit it into the engine using the original manufacturer's components. Boom, you're done.
But what about the spin-ons?
- Does the material filter out all the nasties? And to what micron?
- Does the anti-drain back valve (rubber washer) really stop the oil flowing back into the sump?
- Does the bypass valve open at the specified pressure for your bike?
- Is the filter element sealed correctly within the canister? Hmm...
Take a look around the net and read about filter reviews, the good, the bad and the downright ugly. I've been a mechanic for a long time and screwed on thousands of filters. And as long as they screw on, happy days. You get the odd leaker, or bad thread, and that's to be expected with a mass-produced unit.
But it's all fit and forget. You never look inside one, and don't know if it's done its job. In a garage, it's all completed in minutes. You don't look at the oil that comes out, couldn't care less about the old filter and send the vehicle on its way for another 20,000 thousand miles (or less, as the case maybe). And that's the harsh reality. You're relying on the fact that the filter is a quality component.
But when an engine fails, can you prove it was the filters fault?
I've just changed the oil on the CBR as it was slightly murky. According to the handbook, Honda recommend an oil change every 12,000km (8,000 miles), or at one yearly intervals. That's what some people don't understand, it's whatever comes first. If you only do a couple of thousand miles a year, you still change the oil, not wait until four years later when the odometer clicks over to the correct figure!
If the previous owner has followed the book, but not understood it, it might only have had two changes in its life! Strewth, that ain't good.
Filter quality — how to choose.
I'm guessing for most people it'll come down to availability and price. Being involved in the car industry, especially filter sales, I see price being the driving factor quite often. But some are sticklers for quality, and will spend the extra for peace of mind.
When it comes to my own bikes I always buy genuine. Even in the old Suzukis that have been sat around for thirty years, and they just take a paper element. I just prefer to spend that little extra to know they're approved by the maker of the bike and, hopefully, that means I'm getting a filter that filters.
Unlike the generic brand pictured above.
WTF? No manufacturer's brand name. Just basic instructions in English and Japanese. I thought it would be worthwhile sharing this little beauty to give you an idea on what might happen inside.
For those that don't know, the oil filter needs to be able to perform the following duties:
- Protect the engine from harmful swarf and particles etc.
- Provide good oil flow at all times
- Prevent oil draining back down to the sump when the engine is off
- Still allow oil flow, via a bypass valve, if the filter gets blocked
- Be strong enough to remain oil tight while taking the odd stone chip etc.
All that and you want to save a few bucks on a cheaper filter?
The ugly truth about cheap filters.
So let's open one up. First pic shows the top part of the filter that screws on to the engine. This rubber seal has two jobs:
- Anti-drainback valve — so when you start the bike oil is already there in the filter ready to be pumped around. There's no delay waiting for the oil pump to build pressure first and then fill the oil galleries.
- It also seals the filter element to the top of the filter assembly. Without this, dirt could potentially get through and be pumped through all the bearings.
This seal is slightly offset, due to bad assembly or a misshaped filter element.
The view from the other side makes it more obvious. It should sit snugly against the top to prevent the oil draining back when the engine is off.
If you look closely you can see the markings on the rubber seal where it hasn't been sat completely true. The rubber is now deformed and this was probably due to an assembly fault.
The element does have metal end caps, but has deformed on one side because the seal was not fitted correctly. The spring in the bottom of the canister maintains pressure on the element to keep it against the rubber seal.
On this side you can see the slight deformation. It's not horrendous, but could be enough to let the oil past the seal instead of going through the filter. Hopefully spring pressure helped to keep a good seal at the top. If not, the dirty oil could just flow out through that instead of through the paper element.
In the unfortunate event that your filter blocks up, a valve is fitted to allow unfiltered oil flow through the engine. It's obviously better to have any oil flow rather than no oil. These are designed to work at a certain working pressure, such as 8-10psi and, in my opinion, the best ones are fixed to the metal disc at the bottom as they're much sturdier.
In fairness, you don't see blocked filters too often nowadays, unless the vehicle hasn't been serviced for ages (as in missed several services but continued to clock up loads of miles).
In normal use it remains closed.
And pushed open, it allows oil to flow straight thorough the middle and back into the engine.
How it looks from the inside. The steel dome in the middle retains the spring and plunger.
To conclude — don't scrimp.
There's plenty of places to save money, oil filters aren't one of them. There's plenty of different makes out there, so do some research, buy quality parts backed by a large manufacturer or, do yourself a favour, and buy genuine. At least if their part fails you can send it back. Oh, and stick to the recommended service intervals.