I have a Volvo 850GLT wagon. In the winter I used Mobil 1 5W30 synthetic. Now I want to use Mobil 1 10W30 synthetic. The garage, do to cost wants to stop using Mobil 1 and recommends German Lubro Moly Voll-Synthese 5W40. Which oil should I use Mobil 1 10W30 or Lubro Moly 5W40? I read somewhere on the net that to big of a range between low and high viscosity rating is no good. Adam
I use Mobile 1 5W30 synthetic year round, never had a problem with it.
I use that exact oil in my cars, and have since new, or when I first got them. I don't think there's a lot of difference pricewise between it and Mobil 1, I use the Lubro Moly because it easier for me to procure.
What you've read about wide range multigrade oils applies to some conventional oils, because they need to use additives to achieve the "multigradeness". These additives have large molecules that can break down under stresses in the engine. These additives are not needed as much in a synthetic oil, with is naturally multigrade to begin with. My V70 T5 which I bought new in 1998 has seen nothing but Lubro Moly 5W40 since 8000 km, and had absolutely no varnish buildup with 8000 km changes. It now has 135k km.
The Lubro Moly 5W-40 synthetic is one of many very high quality oils currently available and will be fine in your GLT.
John
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