Question on True Synthetic oil (5.4L)

[JExpedition07]

I changed my oil and used Mobil 1 High Mileage Full Synthetic. Mobil claims boosted levels of seal conditioner in this product which is why I chose it for the chain tensioners. My question is what makes an oil truly synthetic? The Mobil 1 says Full Synthetic, but then some bottles say 100% Synthetic. Are they all blends besides the 100%? I always have used Motorcraft Synthetic Blend in the past. There are also crazy expensive oils that I’m not sure why anyone would take off the shelf for a daily driver.

 

[07navi]

I just changed my oil and used Mobil 1 High Mileage Full Synthetic. Mobil claims boosted levels of seal conditioner in this product which is why I chose it for the chain tensioners. My question is what makes an oil truly synthetic? The Mobil 1 says Full Synthetic, but then some bottles say 100% Synthetic. Are they all blends besides the 100%? I always have used Motorcraft Synthetic Blend in the past. There are also crazy expensive oils that I’m not sure why anyone would take off the shelf for a daily driver.

Full is 100%. Synthetic is just highly refined regular oil with added conditioners. The molecules are actually smaller and more uniform so probably worse for tensioner leaks. Those tensioner seals are either working well or blown out anyway. I was thinking about using Permatex #1 on them next time I replace them. I wouldn't let them influence your oil buying though. There are more powerful seal swellers out there but I doubt if any would have any effect on the tensioner O rings.

 

[JExpedition07]

Full is 100%. Synthetic is just highly refined regular oil with added conditioners. The molecules are actually smaller and more uniform so probably worse for tensioner leaks. Those tensioner seals are either working well or blown out anyway. I was thinking about using Permatex #1 on them next time I replace them. I wouldn't let them influence your oil buying though. There are more powerful seal swellers out there but I doubt if any would have any effect on the tensioner O rings.

I was having a cold start rattle from the tensioners in the morning so I added seal conditioner agent to the oil about 3,000 miles ago and it has made the rattles go away. Cold starts have been quiet now. I figure this oil will help prolong the seals some. Thanks for clarification on the 100% synthetic vs full synthetic. That was my suspicion that the 100% was the genuine stuff.

 

[07navi]

I was having cold start rattle from the tensioners in the morning so I added seal conditioner to the oil about 3,000 miles ago and it has made the rattles go away. Cold starts have been quiet now. I figure this oil will help prolong the seals some.

Great if it worked but synthetic will leak easier than regular oil which is probably why they add seal swellers (if they did) and I doubt if there is much in it compared to a dedicated sealer. The temperature has an effect on the tensioners also (worse on cold days). I think oil pressure on start up affects them also so when you do fix them a better oil pump might help. I think Melling makes one, and make sure you use Motorcraft filter with the good drain-back valves they have in them.

 

[JExpedition07]

Great if it worked but synthetic will leak easier than regular oil which is probably why they add seal swellers if they did and I doubt if there is much in it compared to a dedicated sealer. The temperature has an effect on the tensioners also (worse on cold days).

So far so good, I changed to the Mobil 1 two days ago and she has still been quiet on cold starts. These tensioners still blow out on the newer 5.0, EcoBoost, 6.2 engines too and they get the same rattles in the F-150 trucks. You’d think they’d spend a buck and put in cast tensioners.

 

[07navi]

So far so good, I changed to the Mobil 1 two days ago and she has still been quiet on cold starts. These tensioners still blow out on the newer 5.0, EcoBoost, 6.2 engines too and they get the same rattles in the F-150 trucks. You’d think they’d spend a buck and put in cast tensioners.

Or cast ones with JB weld…………..lol

 

[JExpedition07]

Or cast ones with JB weld…………..lol

From my research the seals fail in 2 main ways. Sometimes they blow out in a spot and other times they flatten out and start to whither like a pancake. I’m guessing mine were doing the latter since seal sweller helped the situation. The older engines used simple cast ratcheting tensioners that had no problems. Here is the updated tensioner vs an old leaker with the OEM whithered seal.

 

[07navi]

I think the main improvement is when they started putting a ridge around the perimeter that contained the seal and recessed the O ring on both the cast and plastic ones. They are definitely a one time use item. I am surprised with all the smart engineers out there they can't contain oil under pressure on a part like this.

 

[IIGood]

I am surprised with all the smart engineers out there they can't contain oil under pressure on a part like this.

...but....COST!! That's $.07 part will jack the price of the vehicle up by $5000!!!

(kidding, of course, but a semi-truth there perhaps)

 

[Shantheman73]

I was having a cold start rattle from the tensioners in the morning so I added seal conditioner agent to the oil about 3,000 miles ago and it has made the rattles go away. Cold starts have been quiet now. I figure this oil will help prolong the seals some. Thanks for clarification on the 100% synthetic vs full synthetic. That was my suspicion that the 100% was the genuine stuff.

Please tell me what you used! I’m having same rattles on start up...


2007 Ford Expedition Limited
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