Secondary Filter Kits

Which Kit? Primary or Secondary?

WHAT’S THE DIFFERENCE?

Diesel Care offer D.I.Y. fuel filter kits in two variants for most of the vehicle range we cover; Primary (pre) and Secondary (final).
We’ve had a few people ask what the difference is between our Primary and Secondary Kits, so we’ll explain.

FUEL MANAGER - PRIMARY (PRE) FILTRATION

Primary filters, sometimes called a pre filter are plumbed before the factory filter.
(See image A below.) Fuel passes through this relatively coarse filter first before continuing on to the vehicle’s factory installed filter, then to the high pressure pump. The filter media in a Diesel Care Fuel Manager primary filter is rated at 30 micron. A micron is a unit on length equal to one millionth of a metre, or to break this down further; one micron is one thousandth of a millimetre. 

So, a 30 micron filter will remove particles the size of 30 x 1,000ths of a millimetre. This may sound very small, and it is, but not small enough to protect modern high pressure fuel systems from abrasive damage. Most factory filters on modern Common Rail systems are rated at 10 micron.

FUEL MANAGER - SECONDARY (FINAL) FILTRATION

Secondary filters, sometimes called a final filter are plumbed after the factory installed filter.
(See image B below). Fuel passes through the factory filter first before continuing on to the secondary filter, then to the high pressure pump.
The filter media in a Diesel Care Fuel Manager final filter is rated at  2 micron or 5 micron, depending on the vehicle. So, a 2 micron final filter will remove particles the size of just 2 x 1,000th of a millimetre. Now that is very, very small!

SO WHICH ONE DO I CHOOSE? PRIMARY OR SECONDARY?

This is where you need to decide. There are a number of differences between both options, and a lot of people ask
what we recommend. We’ll get to that later but first we’ll go over the features for both.

PRIMARY (PRE) KIT FEATURES
•    The 30 micron Filter effectively removes larger particulate matter
•    Effectively removes water
•    Prolongs the service life of the factory filter cartridge

Additional Info
•   It is recommended that you change the primary filter
    cartridge at the same time as you would your factory filter unless fuel is contaminated.

SECONDARY(FINAL) KIT FEATURES
•    Provides an effective safety net if contaminants get through the factory filter
•    The 2 and 5 micron filters effectively remove smaller abrasive particles, resulting in less wear on the pump and injectors
•    Effectively removes water if any gets through the factory filter

Additional Info
•    The secondary Filter cartridge can be changed less regularly than the primary and factory  filter cartridges, we recommend every second time the factory filter is changed unless fuel contamination occurs.

WHAT WE RECOMMEND...
Both options will provide much better protection than not having an additional filter. Each one has their advantages but at the end of the day, we recommend secondary.

The reason is that we believe that finer filtration ultimately provides better protection. It’s also reassuring to know that if you are unlucky enough to get a bad tank-full of fuel, and the filter warning light on the dash comes on, that if anything has penetrated your factory filter, it’s been caught in the final filter. The fact is; contaminants DO get through filters. As Diesel Injection Specialists we see evidence of this almost daily. The best way to prevent expensive repairs caused by fuel contamination is to filter it. Fuel cannot be too clean.