oil differences? -- High Mileage vs. Synthetic

[monterey1962]

I picked up a case of oil today. I buy Cenex Auto Gold 10w-30. As I always do, I just grabbed the top box of 10w-30 off of the pile in the store. Got home and noticed that there is a difference from the case of oil I already have.

Both are Cenex Auto Gold 10w-30. One is marked "For High Mileage Engines" and the one I bought today is marked as "Synthetic". I compared the wording on the bottles and there doesn't seem to be much of a difference. Only thing I really found was that the "High Mileage" oil helps to keep the seals in better shape. Does it really matter (engine wear-wise) if the one I picked up says "Synthetic"? I always use a bottle of Lucas Oil Treatment when I change oil, anyway. Just thought I'd see what you guys thought. Btw, there were no visual differences in the boxes or the bottles other than the fine print.

[Chevyguy]

You got a bargian, Synthetic oil usually costs a good deal more than regular oil.

The synthetic should do a better job of burnoff resistance and viscosity retention. This is good for a old 302 as you see your oil pressure drop at idle quite a bit when the oil breaks down.

[boXman]

Don't mix them, whatever you do. Forget that synthetic crap, unless you want leaks popping up.

[monterey1962]

Don't mix what? The two types of oil or the Synthetic and Lucas? Why shouldn't they be mixed? A little late for me to take the oil back.

[boXman]

The two types of oil.

[87mefull]

Be careful with synthetic oils, It caused a rear main seal to start leaking badly on a friends 89 Taurus with 110k on it. It never leaked oil before he switched to it. I stick to regular oil since it really doesn't help a high mileage engine much and synthetic oil is about $4 a quart.

[87_crown_vic]

personally, synthetic oil costs more to buy and shows you where you are gonna have to spend money. it leaks out easier than regular or high mileage. i only use valvoline 10-40w year round and every other oil change i use the high mileage. i use a thicker oil due to how far i have to drive to work and living in B.F.E. i took Vickie, my white 1987 CV, in for an oil change before and they mhad a synthetic blend. big mistake on my part. now she leaks and cant seem to get all of them fixed. first was the valve covers, than the sending unit, now the lower intake is leaking. my opinion stay away from synthetic or blends. like i stated, i use regular and every other time i use high mileage since it has the other additives.

[monterey1962]

You guys had me thinkin', so I ran down and spoke with my mechanic. They use nothing but Cenex oil. This stuff is a synthetic blend, not a full synthetic. It's in the '91 right now (which I need to change the oil on) and there are no issues. All should be well on my part. Yay for me.

[jasonh]

I just change my oil every 3000Kms :canada: it comes out clean. I don't see a point in using synthetic unless you want to extend your change intervals.

[N A]

Use the synthetic motor oil. I use it and no leaks!!!

[Grand Marquis GT]

If you use synthetic from the get-go, you will REALLY benefit.

[Tiggie]

I'm using synthetic in a newly rebuilt Flathead V8 (8BA). I used the dino stuff to break it in. It was hard to start with that stuff. It also got dirty really fast. Changed it again at 500 miles, got dirty and hard to start. Switched to synthetic, starts easy and stays clean. I'm sold on it.

[gadget73]

I ran synthetic in the VW for heat resistance reasons. Air cooled motors cook oil in a bad way. 300 miles and it would be black with conventional oil. Blends were good to about 1000 and full synthetic let me do the reccomended 2500 mi oil changes with brown oil instead of something that looked like roofing tar. I ran the first 15k or so in the Lincoln with regular oil, and I've got synthetic in it now. The truck has 140k and always had dino oil. Doesn't leak a drop and at this point I'm scared of changing to synthetic.