Can a failed DPF regen cause oil contamination in the engine?

My 2013 Mazda 6 diesel recently had a low oil pressure warning light come on. I stopped driving immediately and got towed to my Mazda dealer. They changed the oil and said it was contaminated (they didn't specify with what) but I'm assuming it's excess oil from too many failed active DPF regens. I know this is common on these cars. It now does mostly city driving so I'm sure this is what's happening.

My main question for you is: what is the most effective way of avoiding this happening again? I've been looking at DPF cleaners. Would using something like this on a regular basis help or is it a waste of time? My local garage also offer six monthly DPF cleans, not sure exactly what this entail but could this be worth a try?

Asked on 29 November 2016 by djolord

Answered by Honest John
You have correctly analysed the reason for your problem: Repeated short runs from cold starts. The DPF starts to regenerate passively after 20 miles of driving and burns off the soot in the DPF from its original cold start. It also regenerates actively (by introducing extra diesel to start a fire in the DPF) every 250 miles or so. But if the DPF is too clogged with soot, the active regeneration cannot take place and the extra fuel dribbles down the bores contaminating your lube oil and raising its level. Decent superfuel such as Shell V-Power Nitro Plus helps (I ran a Mazda 6 Skyactiv on it for 14,000 miles, no trouble). Stuff like 'Cataclean' might help but I can't recommend it because I've had no positive reports. Good to change the engine oil anyway every year or every 10,000 miles whichever comes first.
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