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Resident Mechanic
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Discussion Starter #1
98 4.3 with 90k on it, abot to change to castrol synthetic what weight should i got with? I am using castrol 20w 50 right now and have had alot of people tell me thats too heavy
 

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Fast98SS350 said:
98 4.3 with 90k on it, abot to change to castrol synthetic what weight should i got with? I am using castrol 20w 50 right now and have had alot of people tell me thats too heavy
Good lord why are you using that heavy of oil?
 

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exactly what mighty mouse said. WTF are you doing! drunk and pressing the wrong buttons on the keyboard? I was thinking of going to 10w30 and THAT was a little heavy! Holy CRAP!:rolleyes: :bash: :drinkhaha
 

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mtl_hed said:
exactly what mighty mouse said. WTF are you doing! drunk and pressing the wrong buttons on the keyboard? I was thinking of going to 10w30 and THAT was a little heavy! Holy CRAP!:rolleyes: :bash: :drinkhaha
Uhhhhh Mighty Mouse?
 

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Resident Mechanic
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Discussion Starter #5
Yea 20w50 is what i have always used, get a strange reaction everytime I tell someone and I didnt wanna change it without asking someone first cuz i dont wanna go too low but I was good low enough to get the best performance so what u guys think i should use?:confused: :D
 

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Fast98SS350 said:
Yea 20w50 is what i have always used, get a strange reaction everytime I tell someone and I didnt wanna change it without asking someone first cuz i dont wanna go too low but I was good low enough to get the best performance so what u guys think i should use?:confused: :D
I would use 10w-30 if I were you.
 

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synthetic oil weights

freakin ****** - 20W50 is way too heavy - you're probably using up 5-10 hp just sloshing that jelly around in the crankcase!

i've been running 5w30 or 10w30 mobil 1 since i pulled my first engine apart 15 years ago and had a close look at the crap paraffin based oils leave in your engine. i also like (cringe) wal-mart's super tech fully sythetic - the one in the gold bottle. flame away if you must but i've found it stays clean as long and does just as well as name brands.

on a motor with that many miles, you're going to have dirty oil in that thing just about forever because the synthetic oil will slowly (and i mean very slowly) dissolve the varnish and crystallized paraffins from within your engine. on older v8 smallblocks, i've seen _POUNDS_ of burned up oil stuck to the bottom of the intake manifold - caked up so bad i had to bust it off with a cold-chisel. go get you some crankcase flush and run it through there before your first 5 - 10 changes - that will help break up the junk. also, dont run any of the synthetic blend crap. most of these are predominantly paraffin based - spend the extra buck or so and get the real stuff.

as far as what weight to use - unless your bearings are really worn - you'll be fine with either 5w30 or 10w30. the big difference with synthetic oil is that it doesn't change viscosity any where near as much as paraffin oil when temperatures change, so you'll be safe with 10w30 unless you see -30 degree (F) temps regularly. the other nice thing about fully synthetic oil is that it doesn't break down, so if you keep it clean you can run longer between changes. by keeping it clean i mean don't run cheapazz filters - get a decent mobil1 disposable filter from your local autozone, or if you're not afraid of a little more work get one from amsoil that you can take apart and clean the screen out on. these are relatively expensive (around $60), but they do a much better job of trapping particles. i ran my '94 v6 camaro an average of 12,000 miles between changes, and after tearing it down (blew a head gasket) at 165,000 miles the crank journals and cylinder walls miked out to original specs.
 

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T/A drivin foundin member
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im runnin 10-40
 

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MO. boy missing St.Louis!
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Oil........

I used to run Castrol 10w40, now I'm using Castrol Syntec 10w30 and have used the 5w30. My engine runs a lot better and gas mileage is around 20 to the gallon on HWY.
 

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i use 20/50. of course, i live in 110 degree heat....
 

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Purple Pavement Pounder
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AMSoil

I have been using AMSoil on my truck since it had 3 miles on it in 94. I now have just shy of 347,000. I believe this stuff is a big part of the engine going so long. Expensive but worth it, ofcourse being a dealer of it makes me a little into it.
 

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T/A drivin foundin member
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ONEBDGMC said:
im runnin 10-40
castrol syntec of course


later i may switch to red line
 

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viscosty matters

When I primed my crate engine, I started w/ a small 1/4" electric drill amd it reved up 'till the oil started to flow back into the dstributor hole. It started to smoke from the effort moving 10W-30 castrol (GTX). @ 5,000 mi. we justd swtched to syntec 10W-30.
BTW the 5W-30 was detroit's way of trying to help the CAFE mileage. The switch to thinner oil gave better EPA mileage tests.
 

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Death Metal Head
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Little late posting

But I read somewhere if you really waqnt you S-10 V6 to run forever use 3 quarts of regular 10w-40 (whichever brand you like) and then add 2 quarts of 15w-50 synthetic. Thats what I do.
 

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T/A drivin foundin member
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ive always heard not to mix weights and brands
 

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don't mix oils

each brand and each grade of oil is it's own package of a mixture of additives designed for that specific grade. I work in the tank truck industry and I can tell you that there is alot of different items used as oil additives. I would not mix additive packages, it might degrade the other oils ability and decrease the over all lubrication in the engine.
 

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V8 S15 Jimmy & V8 S10
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I use 20W-50 Valvoline in my 4.3 in the SUMMER time.
In the winter, I use 10W-40 Valvoline. Works great, when I did the intake swap, the oil gallery was like it was brand newin there!
I got about 1800 on my oil now, and I just pulled the dipstick the other day and it looked like I just did an oil change on it! Of course. right now, shes got it 10w-40.

later guyz
 
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