Mazda 1.8L, M1, and Texas "Winter"

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Dec 4, 2002
Chico, TX
I put winter in quotes because it isn't much of a winter compared to the rest of the country.

I have a '96 Mazda Miata with a 1.8L DOHC and I've been using 10W-30 Mobil 1 SS ever since I purchased the car. It has 130,000 miles on it now, I got it with 124,000 miles. I have no idea what was in the crankcase when I got it, but I immediately changed to M1 and a SuperTech filter. I waited 2,000 miles (a kind of simple "flush" in my eyes) and changed out the M1 and then used a Wix filter. Strangely enough, the Wix called for in this engine is the same as my VG33E 3.3L V-6 in a '97 Nissan Pathfinder, 51356. I lost no oil between changes.

The oil has been in for 4,495 miles now, and I got some HLA noise on cold startup yesterday morning. It was 40F, so I attributed it to the oil thickness when cold. I bought some 5W-30 M1 SS to do a oil change, and I checked the oil before draining the old oil. I had lost half a quart and the oil had turned black. This concerned me, but then again I have a '77 T-Bird that does the same thing. When it is ready for a change, the oil will darken and it'll start consuming oil. I was going to try 5000 mile intervals with this car (as with my Pathfinder) but it seems it doesn't like that idea. The only change in driving habits was a 500-mile round trip to Houston over Thanksgiving. I have a 120-mile round trip commute each day.

Would a 5W-30 be recommended for winter in Texas, the coldest we've gotten so far is 26F overnight. The manual states that 10W-30 is good all the way down to 0F. Anybody have experience with this engine and change intervals? It is the same 1.8L used in the Protege. I know I should do a UOA, but I don't see that happening too soon.
Stick with the 10w30.
I don't think there will be much difference in performance between Mobil 1 5W-30 and 10W-30. Have you considered using Mobil 1 0W-40? Since the 0W-40 is thicker at normal operating temperature it may lower your oil consumption slightly and it should work as well as Mobil 1 5W-30 or even better in the winter. I have used Mobil 1 0W-40 in my wifes 1997 BMW 318i with the 1.9L four cylinder engine and it seemed to work very well. Oil consumption was very low and it did start faster on cold days than when I had been using Pennzoil Long Life 15W-40. I would suggest using Mobil 1 for at least 5,000 miles or six months between oil changes. It should only need to be changed more often if you are racing the car or if you are having mechanical problems.

[ November 29, 2003, 05:29 PM: Message edited by: Sin City ]
I would stick with the 10w-30 also. It is what I use in my 2001 miata. The HLA noise is kind of normal for your car. Some user have been able to cure it by going with thicker or thiner oil but seems to be no consistancy to it. I would do an auto-rx to clean it out as it seems to have a dirty or slightly dirty engine. I go 5000 miles on this stuff and it only turns slightly brown after this milage.
I know a lot of people like to use 10w30 since with some brands of oil it's more shear stable, but when it comes to Mobil 1 5w30, you can truly use this oil all year round, even in hot climates, since it does not thin out like the old TriSynthetic formula used to. So honestly, what benefits do you get with using Mobil 1 10w30 over it's 5w30? The 5w30 will flow faster on a cold start, even if it's 90 degrees outside. I don't see any lower wear numbers in the UOAs posted here with 10w30 M1 over 5w30 M1 either.
The 5w30 seems to have 99% of the performance and shear stability of the 10w30, so yes it is quite feasible to use it in any climate.........but the 5w30 doesn't seem to produce lower wear numbers than the 10w30, so I would guess that quicker flow at startup in moderate climates is negligible. I have never put a 10w30 in any of my newer vehicles, but it doesn't stay 29 degrees in the winter around here either.
I agree with Patman, Mobil 1 5W-30 will work as well as or better than Mobil 1 10W-30 in your application (at least during the winter). I still prefer 0W-40 since it is a little thicker at high temperatures. I also agree with TR3-2001SE about using Auto-RX to clean some of the crud that must be in any motor that has over 100,000 miles.

[ November 30, 2003, 02:11 AM: Message edited by: Sin City ]
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