ScoobyNet.com - Subaru Enthusiast Forum

There is alot of confusion when it come to oil, the biggest being that the highest value is the best, ie 15 cold or a 60 hot weight, its total bull, and this is where it goes wrong.
THE most important part is the cold weight as THE greatest amount of wear is when the engine is cold, a 5w gives more protection than a 10w and a 10w gives more protection than a 15w, and where as I really do like the 15w50 oil a 10w50 gives better protection, a 5w40 gives better protection over all than a 10w40 etc.
There is abosolutely NO need for a 10w60 in a standard or near standard (basically anything under 500bhp) subaru, you can run a 10w50 happily, for 400 or less a 5w40 fully synth is more than adiquate, consider this, the new bmw M3 with over 400 bhp will be running a 5w30 oil....
Do you see what i am getting at?
Thicker is not always best, 30 or 40 years ago it probably was but modern oils are far better with far less shear than older mineral or semi synthetic oils, but stick with the basics for the engine, a classic should never run a 5w30 oil and that is from the manufacturer (unless extreme cold temps and then never over rev the engine), 5w40 was specifically made for classics in the UK by Mobil for Subaru, there you go, these people developed the engine so understand it better than pretty much anyone else.
New age cars are different again as they took into condsideration the new manufacturing techniques so new age cars can run a 5w30, note that subaru do NOT recommend a 0w cold oil for their cars, so stick with their advice.
You have a guy here who has had his car run on a 5w30 oil for 90k miles! why should he change to a 10w50 if its not drinking oil?!
If the car runs fine on that oil then its doing what it should, lubricate.
Then you get the people who say "oh my oil is black after 1k miles, I must change it", Why?!!!
Oil is meant to turn black, thats the entire point of it, it removes carbon and dirt from the engine, if its always a golden colour then its really not doing its job or you have an engine that doesnt produce carbon (saying that i did have a 1.8 phase 1 mondeo that did 10k and the oil was really not bad, probably down to long distance driving rather than town driving but again that is a different story).

We had some guy come on here saying that all cars should run a 0w20 fully synthetic oil, ok in theory he was right but not every engine is the same, a manufacturer will find the BEST oil to give the BEST protection for the LIFE of the engine for NORMAL use, note that.
The guy refered to an American guy who ran several top tier performance cars (as in Italian supercars or German supercars), the ultimate part was where this Yank drained all the oil out of a Ferrari which had a 5w30 oil in and put something different in, started the car (now he left this car for a good 12+ hours so ALL the oil drained out), didnt crank it or anything and he said it made a god awful noise for about 30 seconds (bye bye bearings) then ran smoothly, do that in a subaru and you are screwed.
Each and every car is different, most modern car run one of 2 oils now, a 5w30 fully synthetic or a 10w40 semi syntetic, and the reason behind this is that they really dont need much more, modern oils are very good compared to what we use to have, if you want proof then fit an oil temp gauge, if it gets too hot (ie 120+degrees) then change to something slightly thicker in the hot weight, but do not think that modern oils suck because they have lower values, thicker isnt better and most engine builders will tell you that as an Engineer will say that the closer the tolerence you get, the thinner oil you need, just ensure you pick the right oils for the job and not one that will do overkill, thicker oils can backfire on you and make your engine noisier.
The only time in an engines natural history you need to up the hot value is if it begins to drink oil, that means there is wear there so a thicker oil is the natural fix.

Tony:)