406oc.co.uk

Hello,
would be grateful for any advice, have just changed the oil on my 2003 406 Hdi. I have used 15W 40 Castrol GTX also added 300ml of STP for Diesel engines. Have since found out Peugeot recommend 5w 40 oil for the Hdi engine. I have run the car for about 120 miles without any problems so, far. If I continue to use the car with 15w 40 oil in it am I likely to cause any damage? The 15w 40 meets the recommended BCEA A3/B3 minimum protection, but not the recomended viscosity. Thanks for any replies,
regards,
Tonyredz.

Should be fine although the actual recommended oil for summer and winter is 10W/40 semi-synthetic. Are you sure your 2003 book calls for 5W/40? most on here stick to 10W/40.

If it was me (and I'm really nerdy about oil) I might be tempted to drop it after a month or so and use 10W/40 before winter really gets a grip.

I was once told to put 20W/50 in my 405GR by the parts-numpty at the dealers and I could hardly turn the engine over the next day it was that thick. I was a lot more involved in which oil after that!

Ford Zetecs use 5w30, thicker oil in my old Orion made it cut out all the time!

At least your oil change blunder didn't involve draining the gearbox by accident and putting another 4.8 litres into the engine