02-10-2013, 06:36 PM
I was talking bout this with a guy at the local motor factors a few weeks ago, I had one with it on last service and this time it was without. Apparently it's a option with Framm filters for if you live in a particularly 'dusty' area like a pre-filter, filter. Never did mine any harm, and tbh throughout the summer I would've thought it was better.