In my experience I do the following: (note that I am in New England, and several times each winter, I will need to start the car at zero F or below. Also, I simply do no always have access to a plug for the block heater, such as at work, or on a trip up north skiing.)

I replace my battery every four years...If I had the misfortune to completely drain the battery at least once, I replace it every three. As the battery ages, and especially if it is discharged, the battery will just not crank as long and as fast any more. Cost per year, about $30

Same with glow plugs....as they age, they just do not get as hot...Period!!! Change them every three years. Cost per year, about $15.

Total cost: $45 (say $50) per year, or about a dollar a week

If you double the above times....6 years for both battery and glow plugs... you're only saving $25 per year!! Weigh that against the cost of one day when you cant start your car...especially if the car is your daily driver that you depend on for work, etc. If you consider this your "baseline"....(e.g. if you own a diesel, you have to buy batteries and glow plugs at least every 6 years or so), then your incremental increase to replace them every three is about $25 per year. Hardly worth losing sleep over.

If you live in more moderate climates where winter temps rarely go below freezing, then go 5 years or more on batteries and glow plugs. But if you live where you may have regular nighttime temps below 10 F, and throw in a few sub zero bone chillers, I say go with Duralast battery and bosch glow plugs, and replace every three years!!! Even a Mercedes battery is not that much more expensive!


(I dont want to sound insensitive to the "poor college student" or others of similar means...I was there once.....a little extra "party money" was way more important than dependable winter transportation!!! And now, I'm not exactly rolling in dough!) .

My other winterizing strategies, for "snow belt" conditions: (Note that I expect to drive my diesel for many years....many of these things are "long term strategies"):

1) Run four good snow tires (big ticket item at about $100 per year, but a major safety improvement!). I like having a full set mounted on steel rims, including a spare so I dont have to carry long lug bolts for the alloy spare. Regarding tires, I run 205-70-14s for warm weather...a nice cushy touring tire; for snows, I run stock 195-70-14s (a little narrower).
2) When nighttime temps go below freezing, I plug in my block heater every night I can....avoiding daily cold starts saves a lot of wear and tear on the engine....put it on a timer to go on at 3am.
3) I run dino oil (15w-40) during warm weather, and synth. Rotella (5w-40) Dec. through Feb.
4) A block heater is essential!! Check it in November to make sure its working! Along with my block heater, I installed a little 3 amp two stage batt. charger to go on with the block heater to ensure fully charged battery when I need to crank on a cold morning (I use a nice little weather sealed charger I got from a marine supply store. Also, I wired in a relay to disconnect both the pos. and neg. leads from the charger when not plugged in....I want the charger completely isolated from the battery when not in use)
5) I installed a volt meter (and two 12V sockets) in place of the ash tray, so I always know the alternator output when running, and batt. voltage when not running.
6) I keep a charged battery pack in my trunk in the winter (if 10 below is predicted over night, I take it inside overnight)...I also keep a set of jumper cables in the car.
7) Keep an extra glow plug on hand, in case one unexpectedly fails (even if you replace them every few years you might get a dud)
8) Replace coolant (MBZ only) and flush every 2 to 3 years (yes, I put in water wetter too....I can't help myself)
9) I keep a mono-valve repair cartridge on hand (I keep it in the car in the winter....If you experience a long winter road trip without heat, you will do this!!)
10) clean battery terminals every year, inspect all electrical connections (glow plugs, battery cables, block heater, etc.) and repair as needed
11) I installed a kill switch on one of the hot wires to the automatic antenna....I kill it in the up position in the winter and leave it that way...I hate when it freezes in the down position for my morning drive to work. If I'm going to park in a place that I would worry about antenna vandals (street parking in Boston at night), I just flip the kill switch and retract the antenna.
12) With every fill, I put a little Power Service anti gel in the fuel (even though winter diesel is formulated to prevent gelling, I can't stop myself from doing this!)

Thats about all I can think of....

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)