Oil Pressure on Castrol Magnatec

I have always used the Quantum Synta 10w40 semi from GSF/VW dealers on my 240 but GSF is no longer supplying it and on my last oil change I picked up some Magnatec from Halfords as it is the same viscosity and is a semi as well I believe. My oil pressure is now .5 bar down at speed and up to 1 bar down on tickover when warm. So not only is the pressure reduced but it seems less stable - anyone else experienced this ?? Should I be worried by this ? - I'm not very happy anyway and I'll probably try and source more Quantum hopefully from VW dealers and change the oil again ASAP !

Are you sure you put the 10/40 one in there are 3 viscosities available a 15W40 a 10W40 and a 5W/30. Check the can. My local Maccess 5 months os so ago had a notice up to return any Magnatec as it had been incorrectly labelled. Regards Peter

Good point, it's definitely 10w40 on the can - just checked. I've done a bit of googling and looks like a few people have experienced a drop in pressure changing to Magnatec.