What weight engine oil for a 302?

All 5W is part synthetic. Read the LABEL.

 

I've been running synthetic in my 200 I6 and it doesn't leak or burn oil, no more than 1 quart between changes at around 5,000 miles.

I think it just depends on the engine and not the fact that it was synthetic oil. I mean they also make synthetic specifically for high mileage engines so why would they make a synthetic oil that is going to cause your motor to leak all over the place?

 

Not really very accurate

Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

or to think of it REALLY simple 5W-30 is approx. 30 weight when cold and thins down to 5 weight when hot. that is really just an easy way of looking at it and NOT a true weight to heat ratio.

 

I used to work for an oil company years ago 10W30 and 20W50 are your best two choices

IMO stay away from 5w30 10w40. The problem is that as the amount between high and low number increases, in order for the oil to reach these numbers they increase the amount of polymers in the oil. Which is a main cause of oil breaking down faster. Does this mean you cant use 10w40 not at all, I just feel oil has better protection with less polymer filler in it. Either way if you change your oil more often you will be fine.

 

10w 40 or 10-30 is a good viclosity to run..but of course weight vary depending on youre climate area

 

on a side note...flat tappet cams need phosphurous and zinc
so either find a zinc based oil(they just brought this back several months ago...sl rating?)
or go get some zddplus additive!

 

While I don't have the technical knowledge to dispute what you say, that sounds backwards. If that is true why would say a 10w-40 oil flow thinner out of a warm engine then from the bottle? You could pour it in, warm the motor and drain it and it will flow much thinner from the pan then it did from the bottle, or even flow from the bottle much thinner on a warm day then in the winter.

I have heard what you said before but I can't wrap my mind around that fact.

 

#1 I did look it up and the numbers that are being used such as 5 10 20 30 40 50 are all arbitrary number that SAE Made up in the first place... Don't believe me look it up..,.. Here is the tech article

The weights given on oils are arbitrary numbers assigned by the S.A.E. (Society of Automotive Engineers). These numbers correspond to "real" viscosity, as measured by several accepted techniques. These measurements are taken at specific temperatures. Oils that fall into a certain range are designated 5, 10, 20, 30, 40, 50 by the S.A.E. The W means the oil meets specifications for viscosity at various low temperatures depending on weight, and is therefore suitable for Winter use. 5W is tested at -25C, 10W at -20C, 15W at -15C, and 20W at -10C.

#2 if what you are saying is true and 5W is how oil flows at 0 degrees and 30 is how it flows at 212 then you are saying point blank that 5 weight oil is thicker than 30 because everyone knows that oil is thicker when it is cold than when it is hot.

With that said to disprove your theory why is 90 weight gear oil thicker than any motor oil like even straight 30 weight???

The example that I gave in my other post was meerly trying to give something in laymen's term to make it easier to understand and without going into all the testing and and additives crap that oil goes through to get rated at a certain viscosity by SAE

The way it work is just as above with 5W being tested at -25 and 10W being tested at -20 and so on. They take an oil and lover the temp down to -25 degrees and make it flow at a certain viscosity by adding thing to it and then when it warms up to normal temp it thins out and that is what we call 5W - ?? then they heat it up and add stuff to it until at a certain temp it won't break down and flow any faster than 30 and with all those things added and the hot and cold you get 5W-30 then they take oil and drop the temp to -20 degrees and add stuff until it flows at that same viscosity and when it warms up you had oil that we call 10W you get the picture.

But in laymens terms 10W -30 is the same thickness or same viscocity when hot as 10W - 40 (it is 10W) but 10W - 40 is thicker when it is cold then 10W30 because 10W 40 is 40 "weight" when it is cold and 10W30 is only 30 "weight"

The higher the 2nd number the thicker the oil is when it is cold outside.
at 32 degrees 10W30 is thinner then 10W40 and 10W40 is thinner then 20W50 and straight 90W gear oil at the same temp is thicker then all of them

 

We can all agree that a 30 weight oil is thicker at zero degrees than it is at 210 degrees.Let's say it is the right weight at 210 degrees, but you its zero degrees outside and 30 weight oil is way to thick to lubricate properly. Well, 10 weight oil would be thin enough at zero degrees, but it would be too thin at 210 degrees. So the manufacturer adds modifier to 10 weight oil to give it the lubricating properties of a 30 weight oil at 210 degrees, and return to 10 weight oil properties at 0 degrees.

Does this mean the oil is getting thicker as it warms up? Of course not! Think about it. 10 weight oil at zero degrees will be thicker than 30 weight oil at 210 degrees. 10W-30 just means it's 10 weight oil that has the viscosity of 30 weight oil when it reaches operating temperature. Does that make sense to anyone? Dont take this as gospel, its confusing and I am not sure I even know if what I am saying is 100% correct. Just my interpretation of what I have read.

 

Again, its not that 5 is the viscosity at 0 degrees and 30 is the viscosity 212 degrees as you are implying. The viscosity of 30 weight oil at 210 degrees is going to be lower than the viscosity of 5 weight oil at 0 degrees. You are comparing apples and oranges. Again, 30 weight oil is still 30 weight, weather its 0 degrees or 210 degrees. However the viscosity will change as the 30 weight oil heats or cools.

I like it when you put it in laymens terms so that I can understand it, but this statement is a train wreck. Sorry I gotta go with Acornridgeman on that.

 

You are right about that. It is a thinner 20 weight oil when cold but at operating temps the viscosity modifier thickens the oil so that it will not be thinner than a 50 weight oil would be (at the higher running temperature of 210 degrees)

I figured I didnt get it 100% correct in my earlier post. I said:

Should have said (and changed it to): So the manufacturer adds modifier to 10 weight oil to give it the lubricating properties of a 30 weight oil at 210 degrees, and return to 10 weight oil properties at 0 degrees.

Acornrideman's tech article quote summed it up nicely:

Sorry for the confusion.