My local parts house has a smoking deal going on now for Royal Purple. I have had good luck in all my other cars and now want to put it in the ole BBC for this summer. I'm not good with the weights though......should I run 12w162 or 18w3 ?????:D:D

In other words....I have no idea. I always thought 10w40 but.....???? It's only summer driving and we barely get above 90 degrees in the summer. Hotter than that and it stays at home. Motor runs at a cool 185 reguardless of outside temps. Thanks guys!!!!

What oil you should run depends on a lot of things.

First how many miles is on your existing motor?

What weight oil have you been running so far?

What is the current oil pressure you are running, both cold and hot?

Do you know what tolerances you are running on your bearings (mains and rods)?

What is the intended use of the vehicle? Street, track?

Oh my gosh.......you are making this too hard sir!!!!

Maybe 50,000 on a 460. It's a sunny weather rig that sees no track time. New crank and bearings about 1,500 miles ago. Not clearanced.....STD rods and mains. 50 - 60 psi when cold.......Do you want cruising or idle psi when warm???

This is your typical "drag it out and run it down town" kind of rig. Thanks!

I've been running Rotella since the new cam about 300 miles ago. I think it was 5w.....but not sure.

Ive run Amsoil 10w40 100% syn in my 350 but its not the HP that you have, regardless, I doubt your engine will be upset with a 10w40, remember, at cool temps its a 10 but as soon as its warm, its a 40.
:D

remember, at cool temps its a 10 but as soon as its warm, its a 40.
:D

What in the heck does that mean??? I've never understood the 5, 10 w 30, 40 thing. I'm guessing by the green face that you are joking. Because I don't get the oil/weight thing, it's going over my head!!!!!:(

Come on Jim......straight talk me!!!!:yes:

Mobil 1 15-50. Has the right zinc etc levels for older engines. Cheapest place is Wally World.

What is your warm oil pressure at idle and say 2500? If you are above 60-80 at 2500 then you probably have the right weight oil and I'd go with something similar in a synthetic. I think the Amsoil and the Mobil are good brands as well.

The multi grade oils are designed to change as they get warm. When a 10w-40 oil is at zero here in minnesota, it 'acts' like a 10 weight oil for starting purposes. As it warms up, the oil changes and when fully warm, it 'acts' like a 40 weight. If you had old style 10 weight oil only, as it warms it stays too thin and could cause loss of lubrication. With a straight 40 weight oil, it might not even start up at zero as the oil is like sludge at that temp.
:thumbsup:

What in the heck does that mean??? I've never understood the 5, 10 w 30, 40 thing. I'm guessing by the green face that you are joking. Because I don't get the oil/weight thing, it's going over my head!!!!!:(

Come on Jim......straight talk me!!!!:yes:

No, he's not joking.

Viscosity is the thickness of the oil. The higher the number, the thicker the oil.

We now have multi-viscosty or multi-grade oils. There are polymers added, so when the oil is cool it's thinner and when the oil is warm it gets thicker.

On a 10W-40 oil, when cool will be a 10, but when warm will be a 40. which would be the same thickness. The 10 will never be thinner than the 40 when cool, the 40 will never be thicker than the 10 when hot.

Holy crap, now I'm confusing myself!!! :p

I found this a good read on oil viscosity and it's ratings...

http://www.valvoline.com/carcare/articleviewer.asp?pg=ccr20040601ov&section=hm

Dub's - overall mileage and bearing clearences are key factors in what oil to run. Old school performance was to build loose bearing clearences and run thicker oil like sae 50. Use sae 30 in an engine built for 50 and you are asking for problems. Mileage also has an effect, an engine with 200,000 miles on it is going to be looser due to wear than one with 10,000 miles on it. That's why Ed was asking all the questions.

Outside temps play a big part in oil weight too. If everyday the temps are 100 degs you might want sae 40 or 50 where as if the daily highs only hit in the 40's you might run sae 20.

A new crank and bearings means treat your engine as new for the sake of oil. What oil have you run over the past 1500 miles? You are probably safe with sae 30 or 40 but with tight clearences the sae 40 might create excessive cold pressure.

Up till now I've only mentioned single weights and they are hard to find. Pick you multi-weight as if it's a single weight 1st then factor in the 0w, 5w and 10w rating. On freezing mornings your engine might like 0w. Cold mornings 5w might be better and if it's 50 degs or above when you get moving you could go with a 10w.

Most new car engines have very tight bearing clearences and come recomended with 5w30 unless the weather is extreme in either direction.

I found this a good read on oil viscosity and it's ratings...

http://www.valvoline.com/carcare/articleviewer.asp?pg=ccr20040601ov&section=hm

Dub's - overall mileage and bearing clearences are key factors in what oil to run. Old school performance was to build loose bearing clearences and run thicker oil like sae 50. Use sae 30 in an engine built for 50 and you are asking for problems. Mileage also has an effect, an engine with 200,000 miles on it is going to be looser due to wear than one with 10,000 miles on it. That's why Ed was asking all the questions.

Outside temps play a big part in oil weight too. If everyday the temps are 100 degs you might want sae 40 or 50 where as if the daily highs only hit in the 40's you might run sae 20.

A new crank and bearings means treat your engine as new for the sake of oil. What oil have you run over the past 1500 miles? You are probably safe with sae 30 or 40 but with tight clearences the sae 40 might create excessive cold pressure.

Up till now I've only mentioned single weights and they are hard to find. Pick you multi-weight as if it's a single weight 1st then factor in the 0w, 5w and 10w rating. On freezing mornings your engine might like 0w. Cold mornings 5w might be better and if it's 50 degs or above when you get moving you could go with a 10w.

Most new car engines have very tight bearing clearences and come recomended with 5w30 unless the weather is extreme in either direction.

That said the effect of cold/hot weather on oil is decreased greatly when using a synthetic oil.

FYI i use 15-50 in my camaro 5-20 in my honda ridgeline 5-30 in my toyota prius
ALL Synthetic (oh and synthetic oil in my mowers and pressure washer)

That said the effect of cold/hot weather on oil is decreased greatly when using a synthetic oil.

The "w" in 10w30 stands for winter, if weather temps didn't play a large factor with synthetic oils I think they would have gone back to a single grade viscosity rating.


FYI i use 15-50 in my camaro 5-20 in my honda ridgeline 5-30 in my toyota prius
ALL Synthetic (oh and synthetic oil in my mowers and pressure washer)

Just courious why you choose these viscosities for your different vehicles? Manufacture recomended? The 50 weight is 50 weight be it 5w50 or 15w50, the 15w50 just isn't good in as cold of weather... This really plays out in cold starting and until the engine gets up to operating temps...

Thanks guys for all of the good info. I do know that Toyota recommends only 5w30 for their vehicles and they don't ask where you live. I retired a 4runner with 180K and my '99 Camry has 175K. The Camry literally runs up to about 95+% in performance from when I bought it with 40K. Sure, it's a Toyota but from the day I bought it, it's only seen straight full syn. Do you think the syn blends are just to keep the cost down? I really can't see any other benefit from a blend.

Blends will have same change intervals as reg dino oil. Full 100% syns can have change interval extended, thats one of their benefits.
The 100% syn wont break down nearly as fast so it cleans and lubes longer. :thumbsup:

I do know that Toyota recommends only 5w30 for their vehicles and they don't ask where you live.

My '04 Colorado requires 5w30 as well but says 10w30 is acceptable if the temps don't go below zero (-18C). It flat states not to use (?)w40 or (?)w50. I accidently ended up using 10w40 in my '96 Z/28 SS instead of 5w30 and cold idle the oil pressure guage almost pegged out. That was twice the oil pressure as normal with 5w30.

.....and San Josy gets damn hot in the summer! I lived in Gilroy one summer and had some friends up in Morgan Hill. Do all the cab drivers still dry their hair in the morning and just leave the towel on all day????


(going to hell for that one):p

A couple of reasons the OEM's run a lighter oil viscosity is, as said, tighter bearing clearances and for gas mileage.

The lighter the oil,the less power given up to pump. OE oil fill caps usually have the oil viscosity stated on it. My truck has 10W30, my go-to-work car, one of them has 10W60, the other has 5W30. Thinner oil, less power consumed in pumping oil.

Multi-viscosity oil means at 32°F, the oil is the lighter number to flow better. When temperatures are at 212°F, the viscosity is the bigger number to prevent thinning.

I've never had a problem running early years, say, '90 and older on 10W30. Newer engines have less friction, roller lifters, less weight, etc. and recommend a lighter oil. The heavier oil recommended in the Owner's Manual is mentioned if you're in Bumfolk and the general store only has chain saw oil. A quick fix if you're in a pinch.

The best oil hands down is MobilOne. I work in the petroleum inspection industry, several of us have classic cars with high miles. We bought Royal Purple, Quaker State, MobilOne, Amsol, and a few other brands. The test performed in our engine lab proved that MobilOne held up the best. Our engines are GM crate 350's with about 1500 hours on them. The MobilOne showed more HP, more compression and the viscosity did not break down. We tested all oils the same way, 800-2500rpm for 30 min, 2000rpm for 1hr, and 4500 rpm for 30 min. Since your vehicle has high miles I would recomend the blend, not fully synthetic.

Just courious why you choose these viscosities for your different vehicles? Manufacture recomended? The 50 weight is 50 weight be it 5w50 or 15w50, the 15w50 just isn't good in as cold of weather... This really plays out in cold starting and until the engine gets up to operating temps...

Well the Honda factory recommends 5-20 for my ridgeline and toyota factory recommends 5-30 for the Prius.. and mobil 1 recommends 15-50 for my camaro ... and yes all of these oils are Mobil 1 .. its the only synthetic i use.. hell its the only oil i have used for 15 yrs.

btw I live just outside Washington DC it doesnt get cold here hehe besides the ol camaro is kept in a climate controlled garage so cold starts aren't really an issue.. besides if it gets below freezing round here its only for a few days maybe a week at most.

Mike, interesting testing you did but in actuality there is no 'best' in the country, since all the oils are built with different ingredients and tested in different labs and shops under different conditions.
NOACK volatility tests and Shell 4ball wear tests tell a different story in oils and Mobile one is not always the best. All lubes must meet API testing conditions. It seems there are more people testing all the time and results are always different too. Even the same oil brand and weight will test differently between batches at times.
To say one is 'the best' is of course an opinion based on your tests but other brands have tested better than Mobile One and also claim to be the 'best'.
In general, folks here in Team Camaro can know that the major brands of Synthetics are all good products and worth their price when all their benefits are considered.
Its got to the point with oils that its like Coke or Pepsi, Chevy or Ford, etc. they are all good products but its pretty much impossible to say any of them are 'the best', (except Chevy of course). :D
This is of course just my humble opinion. Im also closely connected to one of those major Synthetic oil companies, formerly employed. :)

Just use the good old Kendal 20-50. Cant go wrong as long as its new oil and changed often.