Semi synthetic or full synthetic

[HTSS_TR]

Originally Posted By: alarmguy
Originally Posted By: tig1
Why would anyone use a semi-syn 0-20 when so many full syn 0-20s are available? Cost? In a $30-$50K truck.

Because engine manufacturers know that conventional oils have a benefit not found in straight synthetics. But bottom line is, no matter the oil, if it meets what the manufacturer calls for your good to go, all apples, just different flavors.

The only advantage of conventional oil is lower cost. There is no other advantage in protecting the engine at any temp and at any engine speed.

 

[CKN]

Originally Posted By: alarmguy
Originally Posted By: geissjr
I just purchased a 2015 GMC Sierra. The truck calls for a 0-20 semi synthetic. Should I continue to run the semi synthetic or convert to a full synthetic? I also have PP 5-30 in the garage from my old truck. If I convert to full synthetic would it be ok to use up the 5-30 in the new truck? My guess is the 5-30 synthetic will have similar properties at startup compared to the 0-20 semi synthetic. Thank you for your input.


I dont see any requirement for semi syn in the 2015 owners manual, just a mention of Dexos.
From page 10-11
"Viscosity Grade
Use SAE 0W-20 viscosity grade for
the 5.3L and 6.2L V8 engines. Use
SAE 5W-30 viscosity grade for the
4.3L V6, and 6.0L V8 engines.
Cold Temperature Operation: In an
area of extreme cold, where the
temperature falls below −29 °C
(−20 °F), an SAE 0W-30 oil may be
used in the 4.3L or 6.0L engine. An
oil of this viscosity grade will provide
easier cold starting for the engine at
extremely low temperatures."

From page 11-12
"Engine Oil Use only engine oil meeting the dexos1™ specification of the proper SAE
viscosity grade. Look for the dexos1 approved logo for GM approved
engine oil. See Engine Oil on page 10-11."

Source...
Click here for 2015 GM Owners Manual


Dexos spec would be semi-syn or full synthetic. My 2011 Silverado w/the 5.3 was factory fill semi-synthetic. In my year the OLM is calibrated for a semi-synthetic. Not sure about the OP's truck.

 

[xtell]

Run the full synthetic. Full synthetics are a lot easier to find anyhow versus semi-synthetics.

 

[geissjr]

5.3 ltr

 

[NH73]

Originally Posted By: alarmguy
Originally Posted By: tig1
Why would anyone use a semi-syn 0-20 when so many full syn 0-20s are available? Cost? In a $30-$50K truck.

Because engine manufacturers know that conventional oils have a benefit not found in straight synthetics. But bottom line is, no matter the oil, if it meets what the manufacturer calls for your good to go, all apples, just different flavors.


It is funny how many people gets too wrapped up in there vehicles they think they have to use only semi-synthetic. As I know of there is none that says to use only a semi-synthetic. For GM, all they tell you is to use a Dexos1 oil. If GM thought that conventional oil is needed, then no full synthetic oils would pass Dexos1.

 

[Nyogtha]

Originally Posted By: tig1
Why would anyone use a semi-syn 0-20 when so many full syn 0-20s are available? Cost? In a $30-$50K truck.


Perhaps a GM dealer with a bulk 0W-20 tank could find a cost advantage this way as long as it's still dexos 1 rated?

 

[CKN]

All dealers make money off their bulk oil storage regardless of the spec. If you look at the cost per quart on the bill-I am positive they are buying the oil in bulk for much less.

The word "PROFIT" even at a dealer IS NOT a dirty word.

If you implying ethics-charging for full synthetic and putting in semi syn-that's another issue.

 

[tig1]

Originally Posted By: Nyogtha
Originally Posted By: tig1
Why would anyone use a semi-syn 0-20 when so many full syn 0-20s are available? Cost? In a $30-$50K truck.


Perhaps a GM dealer with a bulk 0W-20 tank could find a cost advantage this way as long as it's still dexos 1 rated?


I was referring to the customer not the dealer.

 

[Nyogtha]

Um, you did say "anyone", even quoted it yourself

 

[Garak]

tig1, Imperial Oil has a Mobil 0w-20 bulk only option. I wouldn't be surprised if they sought a dexos1 license for it, next.

 

[Nyogtha]

Originally Posted By: CKN
All dealers make money off their bulk oil storage regardless of the spec. If you look at the cost per quart on the bill-I am positive they are buying the oil in bulk for much less.

The word "PROFIT" even at a dealer IS NOT a dirty word.

If you implying ethics-charging for full synthetic and putting in semi syn-that's another issue.


Not implying anything. Not sure what your real point is here.

For example, a GM dealer with a cost advantage for dexos 1 0W-20 blend could offer 0W-20 oil changes at a reduced price vs. the competition offering full synthetic 0W-20 oil changes, and plan on overall increased revenue through similar % markup with higher traffic / volume sold.

Or, such a dealer might keep the oil change cost the same as the competition generating more revenue by simple raw materials cost advantage vs. fully synthetic 0W-20, increasing revenue without increasing traffic / sales volume.

Or . . . any number of alternate scenarios depending on what business model a particular location would support the best. An astute businessperson could explore many different opportunities to find the best fit for their particular situation. Simple business sense - nothing implied at all.

I do not see any constraint of requiring less than ethical behavior on a dealership's part, but that's of course a personal choice.