I almost always use mobil 1 5w-30 in the jeep. Recently Valvoline syn power full synthetic was on sale so I went with that. It's the same weight as the mobile 1 but it's much runnier and less viscous. What's up with that? Should I not be switching oils, is Valvoline syn power a good oil to use. When I put the mobile 1 in the crank case it's like pouring in syrup, the valvoline is like water.

well 5w-30 is a very thin weight oil to begin with. I always liked Mobil 1 and Amsoil when it comes to synthetics. However if your gonna try something new Castrol has a new synthetic out called Edge which was tested and proven to have 8x better wear protection than Mobile 1....IDK. I personally like to stay with the same oil. In my opinion Valvoline is in no way comparible to Mobil 1. I live in Florida and use 10W 30 due to higher temps here and have found that 5W 30 just breaks down much faster in the summer months, if you live somewhere where higher temps are the norm you may want to switch it up to 10W 30.

I always use 5 quarts of Valvoline 10w30 and a quart of lucus oil stabilizer.

I have herd some crazy stories from some of my racing buddies about Mobil 1 saving their engine when their pan got a leak and the engine ran on what mobil 1 was left in the engine... ect ect... I stay with mobil 1 but just my $.02

Valvoline is an exceptionally good product, I personally much prefer it over the overhyped Mobil 1.

And Drivebytrucker, I certainly would not be substituting a quart of Lucas oil stabilizer for the real stuff, all it is doing is degrading the oil's performance. Modern lubricants are very careful blends and adding additives to them are not recommended by any quality oil manufacturer as they totally screw up the blend.

On top of that, Lucas' "Oil Stabilizer" has earned a crappy reputation anyway. Here's just one test of Lucas you should check out. What about Additives? where it is shown to screw the oil oil up so badly that it foams which is evidence of it trapping air.

I'm with Jerry.

Valvoline is a perfectly fine product.

This day in age, its really a chevy vs. Ford type of thing. any 1/2 decent oil will do an acceptable job as long as you change is as directed. (most people change the oil out way before its lubricating potential has been used up.)

Thanks for the heads up Jerry. I actually switched to Castrol high mileage this last change. I'll keep that in mind.

Castrol is very good stuff too, I'd buy that as readily as I would Valvoline. As Mrcarcrazy said, the modern multi-weight oils from the major manufacturers are all pretty much superb lubricants.

I use valvoline and always have.

I was curious because like I said when you put mobil 1 in the crank case it's like pouring in thick syrup and the valvoline was like pouring in water.

Is it bad to switch brands

Oil should never pour like THICK syrup. As the temp get colder, oil will pour slower but it should never by thick like honey or molasses. There are additives that are thick and will thicken the oil (STP oil treatment, Lucal oil treatment, Motor Honey...).

Like others have said, most of the top brand oils are very similar and all that other "stuff" that makes them different from the other brands is just marketing. They all must conform to the same standard.

You're better off spending more money on a better oil filter & using cheaper oil than using expensive oil & a cheap filter.

Well not like thick syrup but you know what I mean, I guess the point is the mobile 1 seems much thicker than the Valvoline of the same weight. I'm not concerned by any means just curious.

Lots of hype about Mobil 1 and that's what it is - hype. I don't think it's as good as or any better than Valvoline, Castrol or Pennzoil, for that matter.

As to additives / stabilizers and such, I don't see a need for them with a quality oil meeting the Vehicle Manufacturer's specifications I agree with the previous Posters that said that already). In fact the Jeep's Owner Manual probably says to avoid additives for the oil.
Don't need synthetic oils either unless one wants additional flowability in winter or longer oil change intervals.

2004 Jeep TJ Owner Manual says:
Jobbers World keeps up to date on what's going on with motor oils.

Here's a Jobber World article on the new Pennzoil Ultra.

This Jobbers World article dated December 13, 2008 is an interesting read.
This Jobbers World article dated Feb 1st, 2009 is another interesting read.

That plus a study several years ago that used to be around on sites like Bob is the Oil Guy where used oil analyses from the 4.0L engine with Mobil-1 oil showed higher than expected levels of iron, which is what the block is made from.

I've always been happy to not run Mobil-1 and those statements from two highly respected oil manufacturers, Valvoline and Havoline, make me even happier I don't run Mobil-1.

Use any mainstream oil and just make sure that you change it at regular intervals. I change mine every 3000 miles and my last Jeep had 250,000 on it and still passed emissions with flying colors before the wife totaled it out. A quality oil breaks down due to contamination long before it loses its lubricating properties due to wear or heat break down. I know the two are correlated, but I will not go into that here as that is quite involved.