You can use 5w year round, it is the same thickness at operating temp as the 10-30. You are gaining extra startup protection with 5w

 

X2^

 

just trying to provoke myths with facts...

 

Thin oil in the cold thick oil in the heat.
I've used GTX 20-50 or 10-30 and Wix filters in every engine I've built.
In Dallas and Sacramento I used 10-30 in the winter and 20-50 in the summer.
I now live in Hawaii and If you live in a place where the temp goes below 32 you should not use 20-50. But in high temps the 20-50 hangs tough, stays in the bearings. ((I have a 65 Chevy Van with a 250 inline 6 I built up. "60 over flat tops 257 duration cam, big valves and ported, Clifford 4bbl intake with a weber 38mm, 2" shorty headers duels and lake pipes.)) 6=8, V8 powerful but runs hot, 210 to 215 all the time. GTX 20-50 stays thick.
Flushing the engine with something like that
can kill an old engine. Simply change the oil and filter again. If you do so regularly(every 2k) the oil will become and stay clean.
periodic maintenance = long life.

 

......think it's officially turned into oil thread. LOL

 

Yeesssss were offf....i love the use 20-50 part , thats awesome.

 

Ooo, Ooo, Ive got to chime in! Any Current 15w-40 diesel engine oil will clean the more dirt and sludge out of your motor better than a gasoline oil. Its safer than using a engine flush, and will lubricate everything very well at the same time. Diesel engine oils have much Higher detergent/dispersant levels than gasoline engine oils, because diesel engines create more soot than gasoline engines. The stable 40 weight of a diesel oil will also help our 4.0s shed less Iron(cylinder walls, rings, lifters and their bores, etc) Ive used 15w-40 weight diesel oils with Good success!

 

Same thing applies to diesel or gas engines and when oil temp below normal operating temp.......lower 1st number flows quicker at start-up so why not use 5W40 diesel oil?

 

so what your saying is you can use diesel oil instead of an engine flush?

 

I'm just saying whatever oil u use, use a lower 1st number oil.

 

X2 or so

 

Probably just been a while since the last oil change. When I bought my old XJ it was abused big time. I had to change the oil about 30 min after my original oil change as it was so full of gunk that it plugged the oil filter.