Motorcraft 5W20 SynBlend Out - Castrol MagnaTec 5W30 In - 2009 GMC

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I bought a used 2009 GMC Sierra last month from a local Ford dealer. As part of their incoming used car inspection about a month before I bought it, they changed the oil and filter and did some other minor work. I was able to get copies of the shop orders, and noticed that they had put in 5W20 oil, instead of the GM-spec'd 5W30 oil. This dealer has a quick-lube section, so they just used their bulk Motorcraft synthetic blend oil. When I looked underneath the truck, I saw a blue oil filter, so I assumed it was a Delco. Today I changed the oil, and it was pretty dark for only 850 miles. The blue filter was a STP filter. I put in Castrol Magnatec Full Synthetic 5w30 and a Delco PF48E. The STP filter had a 9/17 date on it, As I looked into it, I noticed a pea-sized diameter glob of goop on the bypass valve tower, or whatever it's called, that was only about 1/16" thick when I scraped it with a flat blade screwdriver. I don't have a filter cutter, so I couldn't look at the filter innards. I have contacted the previous owner, who used the truck for commuting mostly, and he was good about getting regular oil changes at a shop whose owner I know personally. They usually use Chevron / Havoline products. Did the 5w20 loosen up something? This truck has AFM, but I just put a Range Technology AFM delete on it. I will watch the oil consumption, because before this, I had to add some oil, which was some Dollar General conventional SN-rated 10W30 that I had for my lawnmower. I also put some RMI-25 coolant treatment into the cooling system, since it needed to be topped off. The previous owner had the cooling system flushed / refilled about 2 years ago.
 
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I wouldn't worry about a thing. You changed the oil out early and probably never rev'd the engine to 5500+rpm.
 
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Magnatec has been getting great UOA's. Let us know how those intelligent molecules work. Lol. Enjoy!
 
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Originally Posted by Auae85
I bought a used 2009 GMC Sierra last month from a local Ford dealer. As part of their incoming used car inspection about a month before I bought it, they changed the oil and filter and did some other minor work. I was able to get copies of the shop orders, and noticed that they had put in 5W20 oil, instead of the GM-spec'd 5W30 oil. This dealer has a quick-lube section, so they just used their bulk Motorcraft synthetic blend oil. When I looked underneath the truck, I saw a blue oil filter, so I assumed it was a Delco. Today I changed the oil, and it was pretty dark for only 850 miles. The blue filter was a STP filter. I put in Castrol Magnatec Full Synthetic 5w30 and a Delco PF48E. The STP filter had a 9/17 date on it, As I looked into it, I noticed a pea-sized diameter glob of goop on the bypass valve tower, or whatever it's called, that was only about 1/16" thick when I scraped it with a flat blade screwdriver. I don't have a filter cutter, so I couldn't look at the filter innards. I have contacted the previous owner, who used the truck for commuting mostly, and he was good about getting regular oil changes at a shop whose owner I know personally. They usually use Chevron / Havoline products. Did the 5w20 loosen up something? This truck has AFM, but I just put a Range Technology AFM delete on it. I will watch the oil consumption, because before this, I had to add some oil, which was some Dollar General conventional SN-rated 10W30 that I had for my lawnmower.
I am surpriosed you were ab;le to retrieve the prior owners name. How did you accomplish that, for the dealer obviously doesn't forward private information. Some dealers treat their used car section differently than the new car section. Some dealers that prep their used vehicles only change the oil and not the filter. They are very aware of prospective buyers that check dipsticks. So they want fresh oil there for inspection. So it's possible the prior owner was not aware of the oil filter brand name at the shop where he had oil changes conducted. Odds are, that gunk on the filter was from prior thousands of miles usage. So changing it was likely timed very well.
 

Auae85

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I was able to get the previous owner's name because I found something of his in one of the setback pockets - a Navy challenge coin. Being an Air Force and Army veteran myself, challenge coins are special in their own way. I went back to the dealership and talked to the salesman I dealt with; he told me that the trade was from a fellow employee's relative. I spoke to the other employee while giving him the challenge coin, and found out that it was his brother-in-law's former truck, and that he had attended the same college as my 2 sons, and had played college football like they had. I looked him up on FB and sent him a message; a few days later he responded. I'm sure the veteran connection and college football connection helped. I looked up the oil filter code on the shop order, R84060MP, which is a Carquest number for their house-brand oil filter for the GM 5.3L. Either the dealer wasn't able to get that filter and got a substitute, or it could have been left on from the previous ownership as suggested.
 
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I had 2013 5.3 v8 for very short time. Only complained from people was AFM (causing oil consumption), which you already keeping eyes on. Congrats on new truck.
 
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