Synthetic, Blend, or Conventional Oil?

My wifes truck uses 8 1/2 quarts of Magnatec 5w-30. I use those leftover 1 1/2 quarts and mix with a jug of 10w-30 GTX and use in the Jeep (I use the REALLY large filter, Wix 51773). Since I currently live in North Chicago, I figure that little bit of synthetic will help come winter time. When I get back down to D/FW next year, it will get the same Magnatec that the wifes truck gets.

Edit: changes come at 5K and with a Wix filter.
 
Old thread but I find with any car, if it use to run Conventional and you switch to Synthetic it will sometimes cause a leak. For my jeep I caused a rear main seal leak. Very small but totally not needed leak. Now if your truck has always run Synth then it's not a big deal.
 
Old thread but I find with any car, if it use to run Conventional and you switch to Synthetic it will sometimes cause a leak. For my jeep I caused a rear main seal leak. Very small but totally not needed leak. Now if your truck has always run Synth then it's not a big deal.
Its leaking because you didnt use 20w 60 lol
 
Its leaking because you didnt use 20w 60 lol
i use gear oil 75w 140, conventional ofc. but seriously I did not have a leak before and I got it after switching to synthetic, I happened to not only my tj but my grand Cherokee. My GC started leaking so bad I had the rear main seal replaced and it cost $1000. The tj is a slight drip. Nobody has to believe me here but I saw for myself I created leaks where they were not before.
 
"The proof is in the pudding"
I switched to Mineral high performance 10w 30 a few days after I bought it and not a single leak, But my engine hated it in high temps with strange rattles ticking noises and much concern from me so most recent change I went for Magnatec 10w 40 and its a totally different start up and run, like a non worn engine. :)
Magnatec is a semi synth and it has produced a very slight main seal leak, not enough to cause a single drip so I am not concerned.
The 20w 60 mineral was a total "flaming me" thread I started after a work mechanic told me to use it but I have not, defiantly my oil change after next (I still have 5 Quarts of Magnatec left) I will go 15w 40 or 10w 50.
If you don't live in a cold climate using above 10w 30 is a no brainer its just the purists cant see it cos their non recommended tire size and lift wont let them lol
 
"The proof is in the pudding"
I switched to Mineral high performance 10w 30 a few days after I bought it and not a single leak, But my engine hated it in high temps with strange rattles ticking noises and much concern from me so most recent change I went for Magnatec 10w 40 and its a totally different start up and run, like a non worn engine. :)
Magnatec is a semi synth and it has produced a very slight main seal leak, not enough to cause a single drip so I am not concerned.
The 20w 60 mineral was a total "flaming me" thread I started after a work mechanic told me to use it but I have not, defiantly my oil change after next (I still have 5 Quarts of Magnatec left) I will go 15w 40 or 10w 50.
If you don't live in a cold climate using above 10w 30 is a no brainer its just the purists cant see it cos their non recommended tire size and lift wont let them lol
ah i live in sheer heat 105-115. seen snow 4 times in my life. i just put the cheapest 10w30 in, next time I'll try thicker but if i run conventional long enough it could gunk up the main seal for me. also something about the jeep being literally saying 10w 30 and back then only really having conventional that tells me that's just what we should use, that ticking (idk if MHP is synth) I heard is from synthetic oil use. semi synth sounds like a good choice.
 
10W-30 is recommended.
Isn't an oil weight usually "recommended" by a manufacturer mostly because it strikes the best balance for the multiple global climates their vehicles are going to end up in? There are obvious exceptions to this (5W-20 in the 5.7L Hemi because of MDS, or 10W-60 in a 4.0L BMW M3 because "racecar"), but I'd imagine that often the "optimum" oil weight for a vehicle in the icy tundra is vastly different than that of somewhere where it rarely dips below 0°C and frequently hits more than 35°C.

Regardless, most of the time I'm sure it's just splitting hairs.

Much to this point:
"If you are looking for a good oil to use first check your owner’s manual, then make sure you pick the right viscosity grade and do not be afraid to choose something that has better cold temperature performance because that will help with better startup and reduced energy consumption. Learn about the different specifications and applications oils are designed for, then pick a brand that makes you comfortable. "

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Older European cars used to recommend two different oils weights. One for summer and one for winter. I personally run 10w 30 Napa synthetic year round. I’ve always ran synthetic mostly because I’m im in a cold ass climate and it lasts longer between oil changes. I have no engine oil leaks whatsoever at 108k either.