bargain oil in ASDA (I hope)

[princeperch]

Just picked up 4L of Castrol Magnatec in asda for the sum of £12.00.

Will do nicely for the oil change I'll do in the summer, along with the oil filter I was given by a kind PHr not so long ago.

I assume 5W-30 is ok in the MX5? I don't do track days or rag the nuts off it - so I assume the 5W and the protection this will give at start up is more important that it being a 40 rated oil as opposed to it being a 30 and a bit thinner?

[princeperch]

noone?

[DennisTheMenace]

I use 10w/40 in the snot that stuff is a bit thinner isnt it ? so it may burn it off quicker.

[princeperch]

yeah is a bit thinner but as I only use her at weekends and do abotu 6k/yr this should do the job I would hope..

[skinny]

how old is your car? 5W-30 isn't the best oil, 10W-40 would be much better.

2 reasons

- firstly, the 40 grade gives more protection when warm.
- secondly, your 5W-30 is an A1/B1 spec oil. your car (unless it's a new one) requires an A3/B3 oil. therefore it doesn't meet the required spec. A1/B1 is a fuel economy oil and therefore thins down more in the bearings than the engine has been designed for. check the handbook if you're unsure but def for a mk1, don't use A1/B1 oil.

[princeperch]

Thanks Skinny this is interesting and useful. I picked it up because I recalled reading on a MX5 website (not the oc) that some people use this oil in their cars.

I don't have the guidebook to hand so can't check what Mazda recommend but it is a Mk1 and if you say I shouldn't be using it then I will take it back and get something else..