Fizboy

I bought my truck with 140k on it using conventional oil changed every 3k. I checked the whole truck over for leaks and were none. I then switched over to synthetic and it started leaking at every seal there is on the engine. Somewhere around 190k I decided that it was getting so bad (along with other probs.) that it needed an overhaul. I have talked to many mechanics that have mentioned the same problem. Same goes for transmission and differentials. I say stick with conventional oil until you decide to rebuild the engine or put a new one in. Then switch and you shouldn't have any problems. Just my 2cents. Hope it helps.

TC4RNR

just an update for you folks. i didn't drop the oil pan per your advise. i switched to M1 10-30 full syn about 3500miles ago, so far, there's no external leak but i do notice the engine burns more oil. i check my oil level every week, it seems with Castrol 10-30, it burns 1qt every 3000 miles, with M1 syn, 1qt every 1500miles. but it maybe partially caused by using seafoam right before i switched oil. the mpg is the same, even i added roof rack and 4 lights on top. i've heard roof rack can cause -1mpg or so because of the added drag.

OW3ND

if you don't want to go the m1 full syn route look into rotellaT its super heavy duty...


I ran 10w30 and 10w40 and it seemed a little to light but i didn't want to go 20w50... so i took the plunge into diesel oil 15w40 and never looked back...

diesel oil has high detergent and i go about 5000 per change... when i pull the plug the oil isn't that dirty to boot...

mind you my trucks a 86 with 145k on the clock and i beat on it daily !

GV27

A rack can definitely take more than 1mpg off your mileage.

Sorry I'm in late. Did you use seafoam in the intake or in the crankcase? If you just used it in the intake and you're concerned about sludge you could put it in the crankcase right before your next oil change, go for a drive, then drain it. Or better yet (my personal opinion) do the same thing with BG QuickClean.

That'll clean it out really nicely.

Chris

TC4RNR

1/3 in the break booster
1/3 in crankcase
1/3 in gas tank.

plus whole lot smoooke.

GV27

Ah, you're golden then!

bwhyit

Use the non syn oil. I've used valvoline oil and the OE filters in all my cars/trucks. Changed the oil every 3k miles and never had a engine wear problem. I had a 95 honda from new till 160k and it ran as good as new when I sold it. Compression check, leak down, and dyno test all match "like new" condition within spec. You can argue the pros and cons all day but the benifit doesn't out weight the cost.
Just my opinion.

MMA_Alex

lets add this thread to the long list of stupid threads about oil on yotatech...

i'm pretty sure if you use synth on a car with over 10,000 miles it will squirt oil out everywhere... Actually chocolate milk lubricates better than oil, but the oil companies dont want you to know that.

PCE91V64x4

On new cars, the oil change intervals are anywhere from 5,000-7,500 for dino and 10,000-15,000 for synthetic. Oil is oil (yeah), the difference is additives. The synthetic package better resists heat and last longer before breaking down.

I do not understand the issue with cost. If you use synthetic, use it for longer intervals. If you get it on sale (buy one get one free at Advance Auto right now on valvoline synthetic) it is much cheaper than dino because you do fewer oil changes.

Some are concerned about the oil filter. You can change it and top off the oil (if going for extended oil change interval) or buy a Mobil 1 filter that is designed for the extended service interval.

For those of you in the auto industry, see Automotive News, Dec 3, page 28, "7,500 mile oil change becomes the norm."

Reality is though that if it makes you feel good to change oil every 3,000 miles, go for it!