Can't say whether it was hydrolocked or not, but there was lot of water in the cylinders and at least a pint came out of the exhaust thingy outlet (the mesh bit where the exhaust joins the CATs)
I think the reason it was saved was I was going so slowly and dropped the clutch when I realised what was going to happen.
It definitely wasn't the MAF sensor that tripped the engine but the sensor did put up the engine check light (garage claimed it was dirty )
Grit wise I changed the oil three times over the course of a week, filter twice, and there was a fair bit of sand in there, cream froth and on the first change there was about a cup full of water.
I think i was just VERY lucky, personally I wouldn't recommend anyone using that type of filter in this country, it's not worth the hassle and TBH I thought it was crap, stock is far better but a lot louder at 5000rpm Oh with the Invida.