Dieseldiehard has it right. You want the 75W90 and yes it may help but won't probably make the noise go away. If you haven't used synthethic oil there before plan on changing it again after about 10,000 miles or so because that stuff really cleans out all the gunk.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold