The general consensus is that Bosch and Beru Glow Plugs are the only ones that hold up well. The Beru Glow plugs cost more and are harder to find. The Bosch Glow Plugs are easier to find and entirely adequate.

No matter which plugs you buy you should Ream (there a Glow Plug Reamer for that) or other wise clean the Carbon out of the Holes as it will help them to last longer.
Alternative methods of getting the Carbon out are in the DIY section.

As far as prices go you need to shop around. Find a seller that has a good price on the item and has free shipping if you purchase over a certain amount from them. Buy, something like an Oil Filter to meet or exceed that amount and get the free shipping.

Also if you have not noticed you can keep you Glow Plugs on longer by leaving the Key in the Preglow position even after the Glow Plug Light goes out and can glow for about 20 more seconds. You will hear the Relay click when it shuts off.

Put some Never-seeze type compond on the Threads of the Glow Plug so it will unscrew easier the next time they are removed.

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