In this article, Ryco discusses why some oil filters require higher pressure relief valves

Firmer relief valves means that oil is able to bypass the filter even if it is blocked or if the oil is particularly thick without ever opening unnecessarily, explains Ryco.
If the filter clogs, only then will it open up to allow unfiltered oil to bypass the filter and ensure continued engine lubrication.
For an engine oil pump that runs at higher flows, the normal restriction across the filter element will be higher than in a lower flow system.
The corresponding relief pressure must then also be set higher to prevent the relief valve opening too early and unfiltered oil from entering the engine.
Newer vehicles utilising higher flow oil pumps due to having more camshafts to lubricate and cam phasers (variable valve timing) that run on oil pressure will need stiffer or increased pressure relief valves to ensure oil flows consistently, regardless of whether the filter is or isn’t blocked.
As oil flow through a filter increases and fills with contaminants, so too does the flow restriction. A valve that activates as a result of oil pressure change prevents this from becoming an issue.
Some relief valves are built into the engine block, meaning some filters don’t contain a relief valve.
Alternately, some filters may contain an up-front relief valve so that if the filter clogs, it opens to allow unfiltered oil to bypass the filter and ensure continued engine lubrication.
Normally, this remains in the closed position because the oil flows through the filter media and the oil is effectively filtered and cleaned.

Take Ryco’s Z411 and Z1155 oil filters for example.
On the exterior, both look identical. The dimensions are the same, the thread is the same, however the relief valves couldn’t be more different.
Just because they look the same doesn’t mean that they are always fit for purpose or application, states Ryco.
Other factors such as oil inlet ports and relief valve rating are critical to ensuring filter performance is to manufacturer’s specifications and is appropriate to the application.
Ryco says it is these details that its team focuses on that not only makes its filters some of the best on the market, but also means any new vehicle warranty will not be voided.
This is only one example of several examples that exist in the ever-expanding range of products Ryco currently provides and is developing.
As technology progresses and the development of new engines changes, so too will the capabilities of these relief valves, while ensuring new vehicle warranties are protected.*
Ryco says you can protect the new car warranty of the vehicle you are servicing by using its filters.

For more information, visit www.rycofilters.com

*Conditions apply. Visit the New Vehicle Servicing section at the Ryco Filters website for full details.