Screw Magnatec!
I'm friends with someone who's worked at an autoparts chain for a long time (it ends with *****cheap) and of all the oil they buy in,Magnatec is the cheapest,by a HUGE margin.
Other oils,like Mobil,Valvoline,Penrite etc,they make about an $8 - $10 profit on,max.
Magnatec,I crap you not,they buy in for $8.50 for 4 litres!
That's the reason most garages stock it and push it,it's cheap crap and if your engine grenades,they get to make some more money off you by rebuilding your engine ( A Subaru tech at Wingers told me this,when I asked him why they used Magnatec!).
My car was running 10-30 Magnatec,when I bought it,it had an oil and filter change a month before I took posession...As soon as I found out it was Magnatec,I drained it and filled it up with 10-40 Nulon.
The Magnatec I drained out looked as dark as marmite.
The Nulon's been in the car for three months and is as clean as the day I put it in.
The car LOVES it.
It's quiter,runs cooler and is staying super clean.
Royal Purple did an oil shootout test and Magnatec came in last...WAY last.
Penrite came first,Royal Purple second and Nulon third.
Gotta be an unbiased test for their own product to come in second...