Guys - I went over to synthetic some years ago, and have tended to use either Penzoil Platinum or Mobil 1, depending on what comes on sale when. So now I've got a stash of both kinds, in 5W-20, 5W-30, and 10W-30. The 5 calls for 5W-20 year round, but the Protege & the ancient MPV call for 10W-30 except below -18 C (0 F) when 5W-30 is recommended. Based on what I've read here, there's no reason to keep using 10W-30 at all; 5W-30 should work in the Protege & the MPV year round. Now for the controversial part - although 5W-20 is spec'ed for the 5 in Canada & the US, per the owner's manual 5W-30 is OK for Mexico & Puerto Rico. You know where I'm going with this ... Would it be acceptable to use 5W-30 in the 5? (The engine is the Ford/Mazda 2.3.) That would allow me to run 5W-30 in all three vehicles year round. No more consulting the maintenance records to see what I used to know what to top up with. (That may be moot - with several synthetic oil changes over about 19 months since we bought the 5, it is no longer using oil. The Protege has never used any oil between changes, and I've recently fixed the oil leaks on the MPV, so it may be OK now as well.) In fact, if I could find it affordably here, could I run 0W-30? (Probably not an issue, because I never see it in jugs here - it was $12.xx per litre at Canadian Tire the other night. Add in 13% tax, and it gets expensive.) As far as brand of oil, I think I've settled on Mobil 1. I really like the Pennzoil Platinum, but it just doesn't come on sale as regularly. Just got a good deal on three 4.4 litre jugs of Mobil 1 5W-30 @ Canadian Tire, but I still have some PP 5W-20, PP 5W-30, and M1 10W-30 to use up at some point. (The M1 was 45% off, which worked out to c. $28/jug, which is pretty good for here.) As far as filters, I can't standardize there; I'm running Baldwin B-1402 filters on both the Protege & MPV, but the 5 takes cartridges (also Baldwin). A B-1400 is spec'd for the Protege, but the only difference is that the B-1402 is slightly longer. Have been running the larger filter on the Protege for over nine years with no ill effects. Any feedback much appreciated!