Thanks for the advice. Is there anything official online from Mazda that I can direct the dealer to?
This was part of a document that was on the Mazda web-site under "Support - FAQs", but it seems to have conveniently disappeared.
You may also wish to read back through a few pages on this Forum (link below) to see other the people with the issue.
http://forums.whirlpool.net.au/forum-replies.cfm?t=1979291&p=64
Also have a flick through the Mazda Australia Facebook site (below) and you will see a number of complaints.
http://www.facebook.com/mazdaaus
You should have also received a coloured brochure from Mazda about how and when to check your oil.
CX-5 DIESEL-OIL LEVEL INCREASE- FAQS
Q. Why do I need to check the oil level every 1,000 km?
A: Regular inspection of the oil level is not unique to the CX-5 Diesel. Mazda recommends this for all vehicles. Please refer to the Maintenance and Care section of your Owner's Manual for a complete inspection procedure.
Q: Why is the engine oil level increasing on my CX-5.?
A: It is normal for the oil level to increase above the Full mark on a vehicle equipped with a Diesel Particulate Filter (DPF). The DPF collects particulate matter that is present in the diesel exhaust gas. As part of the DPF regeneration process a follow-up injection of fuel is performed to increase the temperature in the DPF to clear the collected particulate matter. The increase in the oil level is as a normal result of this process, as a small amount of the fuel injected during the follow-up injection adheres to the cylinder wall and is transferred to the engine sump.
Q: What should I do if the oil level reaches or is above the 'X' mark on the dipstick?
A: If the engine oil level approaches or exceeds the 'X' (the highest mark on the dipstick), the oil needs to be replaced with the correct specification oil, Extra DL-1 Genuine Mazda Diesel Oil. Please drive your CX-5 to your nearest Mazda Dealer.
Q: What will happen if I don't change the oil when it reaches the 'X' mark on the dipstick?
A If the engine oil is not changed when the oil level reaches or exceeds the 'X' mark the Master Warning Light and Engine Oil Warning Light will be illuminated when the engine oil reaches the oil dilution limit. If this occurs stop driving your CX-5 and contact your nearest Mazda dealer.