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synthetic vs conventional oil

red_loctite

Full Member
Joined
Dec 29, 2014
Messages
9
Location
Calgary AB
hey folks.  I have heard from a mechanic friend of mine to be careful of running synthetic oil in my 5.3.  I am in Calgary AB wehre it can get to -40c in the winter.  I drive highway 250kms a day or about 40000kms a year.  I will have to have the trans rebuilt this year but i don't want to worry about the engine.  i have 220000kms on it now.  i will be doing plugs shortly, and fuel filter.  my mechanic friend was saying the 5.3 run rougher on synthetic oil.  any thoughts?
chris
 
I've run synthetic oil in all my vehicles since the early '90's.  I don't know what problems it would cause.
 
I run synthetic in my two 5.3s.  I'm the original owner of one of them - it's had synthetic since its first oil change - once with Mobile 1, once with Royal Purple, all of the rest Redline.  That 5.3 has around 462,000 km on it.  It's in an 03 AV so no AFM.  Doesn't get as cold here though, although it can get down to about -25C.  Was around -10C when I drove to work this morning.  Redline costs me about $80 per oil change - obviously I've been very happy with it.

Edit - got an extra 100,000 miles in my km in original post...
 
When I had my 5.3 I ran conventional oil for the 120,000 km it had on it. But when I went to my last two Alum blocks I have switched to synthetic. Is it true that once you go synthetic you can't change back to conventional?
Cheers
p.s. I live in Edmonton so I  understand where you are coming from regarding weather. :p
 
Is it true that once you go synthetic you can't change back to conventional?
Urban Legend look at all the Syn blends on the market.   
 
I was always told to use a synthetic blend and u shouldn't have any problems out of the 5.3
 
JVZL1 said:
Is it true that once you go synthetic you can't change back to conventional?
Urban Legend look at all the Syn blends on the market.   

No, not true.
 
If you have an 09 or newer Avalanche according to the owners manual you are only supposed to use synthetic. 
 
my 2012 requires Dexos, a synthetic blend.  I could continue with dexos (which you can only get at the dealer) or go synthetic, but not conventional oil.
 
You can get dexos approved oil at paets store or walmart.
Example mobile 1 is dexos approved
 
I'm also in Calgary and run synthetic in every GM V8 I own (I have 4).

Read this when you have a half hour to kill:
http://www.bobistheoilguy.com/motor-oil-101/

In short, synthetic is best in cold and in situations where oil sits a long time (Ie. a boat).
 
I have used synthetic oil in all my vehicles for over 10 years its the best and my semi truck runs on it with no problems, And i live in Saskatoon your mechanic friend is blowing hot air up exhaust pipe
 
You can get dexos approved oil at paets store or walmart.
Example mobile 1 is dexos approved

Most full synthetics, like Mobile 1, meet the Dexos spec.  I have not found a synthetic blend that meets the Dexos spec outside of a dealer either.
 
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