Dave, the low SAPS oils are definitely needed for the DPF, (generally sulphated ash <800PPM) and the SAPS levels in car diesels with DPF are far below what is considered low SAPS in heavy duty diesels too, where low SAPS is 1000PPM or below
Just going through this with a PSA Hdi diesel engine which you'd think would be similar/same as the Ford, but no, PSA have different specs again (sulphated ash <690PPM, HTHS >2.9) and so far I've only been able to find Total and Motul easily.
It's a PITA as I have a perfectly good ACEA E4/E6/E9 low SAPS HD diesel oil here in bulk but its <1000PPM SA and the HTHS is a nice, robust 4...... :(

