20w50?

DRock9 · Oct 25, 2006

The guy at Autozone told me that any oil would work in my 1990 mustang as long as it was motor oil. He told me to get the 20w50 in a Synthetic Blend because it has never had anything synthetic before in its life. My Dad just freaked out saying that I cant run that oil in my car...I have no idea who is right but will that oil work fine in my car? And also if not what oil should i get?

Thanks.

EDIT: I know i've searched and I know I should've gotten 10w40 or 10w30 but i couldn't find anywhere that said I could or couldn't use 20w50.

DRock9 · Oct 25, 2006

Also i forgot to say that my car has 116K miles.

1Bad88notch · Oct 25, 2006

with that many miles on your car i wolud use a high milage oil and get 10w-30 or 10w-40.

DRock9 · Oct 25, 2006

I asked the guy there what specific oil I should get and he said "Oil is oil."

I want to make the switch over to synthetic and I got the Castrol Syntec Blend right now so is that no good?

795.0pacecar · Oct 25, 2006

Synthetic is good, and oil is not oil, the guy there should be shot. I personally with a high mileage engine would stick to dino oil and something a little thick like 10w-30 or 10w-40 like was mentioned before.

DRock9 · Oct 25, 2006

Is dino oil the stuff that is in my car currently?

795.0pacecar · Oct 25, 2006

I mean dinosaur oil, meaning it came out of the ground at some point. If you put synthetic in it, then no you aren't using "dino" oil, but synthetic is good and your engine will be fine.

srothfuss · Oct 25, 2006

Also... if your car has oil leaks now, with a synthetic oil those leaks will get worse. Stick with "basic" oil for now.

5-30 in the winter
10-40 in the summer

DRock9 · Oct 25, 2006

Ok thanks, and to my knowledge my car does not have any oil leaks...I plan on supercharging this car within the next few months so would that change anything? I don't have any intentions of getting a new motor until this one is run into the ground, which will hopefully be nothing short of 70,000 miles...

srothfuss · Oct 25, 2006

You base the oil thickness on the PSI your motor can hold at warm idle. and warm cruise.

Shoot for around 30PSI on a warmed up motor at idle. It doesn't have to be exact, but around there is good. Go thicker in weights to get to this point.

In the winter stay with the 5-30 though.

DRock9 · Oct 25, 2006

Ok thanks a lot, ill make my decision but atleast now i know that 20w50 is definately NOT the right type of oil that i need.

Carb'dCobra · Oct 25, 2006

Hey fuss I thought I might ask. I run mine on synthetic 20w50, now it's starting to get a little cooler in the mornings. First I need to connect the choke back up but what oil should I run for now? Morning temps are about high 50's low 60's but temps even out during the day (it's Florida ). Should I change my oil? By the way the motor has 9000+mi on a fresh rebuild.

HISSIN50 · Oct 25, 2006

Carb'dCobra said:
Hey fuss I thought I might ask. I run mine on synthetic 20w50, now it's starting to get a little cooler in the mornings. First I need to connect the choke back up but what oil should I run for now? Morning temps are about high 50's low 60's but temps even out during the day (it's Florida ). Should I change my oil? By the way the motor has 9000+mi on a fresh rebuild.

Was the motor built loose? You shouldnt need more viscous oil on such a fresh mill.

For high milage mills, 20W-50 should be fine. I use it during the summer (highs of 120*F, lows of 80+F). But as Steve so wisely said, you use the lowest viscosity you need to hold hot idle pressure. If this can be achieved with 10-30, I'd use the thinner stuff for quicker start-up flow.

Good luck.

Mustang5L5 · Oct 25, 2006

DRock9 said:
I asked the guy there what specific oil I should get and he said "Oil is oil."

This is why i do not talk to parts store employees.

srothfuss · Oct 25, 2006

/\ That is some good advice right there....

DRock9 · Oct 25, 2006

I don't think I ever will again...

mob · Oct 25, 2006

How cold does it have to be to run 5w30? I live in florida where our winters dont get that bad. Should I just stick with my high mileage 10w30? or go with 5w30?

Carb'dCobra · Oct 25, 2006

I'd go back and ask him again and if he told me the same, I'd be inclined to disembowel him with a wooden cooking spoon, but that's just me.

wicked84gt350 · Oct 25, 2006

First of all stay away from high milage oil I personally dont believe in it. Second the higher the millage the thicker the weight you need and as long as the motor is not slugged up real bad you are fine. The 20w-50 rotilla T is what all the deseils use is some of the best stuff going it has all the protection additives that regular conventional oil has lost over the years. The reason why is conventional oil is cheaper quality now more thatn ever. Also you will be fine with the thicker weight because the w in 20w stands for winter meaning that when in winter the weight of the oil drops to 20 weight and as it warms up it moves to 50 weight multi viscosity. And 10 40 and 10 30 are not all that much thinner. And in florida where i live also it does not get cold enough to really worry about it. It takes like 30 and bellow weather to start to matter. By the way the parts store guy was half right there are only three oil refineries in the world and most conventional oils are the same **** and most semi blends and synthic oils are the same oil just bottled different.WELCOME TO MARKETING.

HISSIN50 · Oct 25, 2006

The statement about 20 weight being what it is in winter is interesting. SAE weights are established at standardized temps (0 and 100*C, as I recall). That's the basis for the viscosity ratings, plain and simple.

Blanket statements about what viscosity oil to run are dangerous. It's like finding optimal ignition timing - it's varies with every engine/combo.

Oils come in many basestocks and with many add packs. A PAO or PAE basestock (or even a Gp III+) is not the same as what we call a conventional (dino) oil. If there's doubt and one suspects a conspiracy, I'd check out some independant VOA's.

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