10w30 oil vs 20w50

[capriceowns]

I have a flat tappet cam in my engine, so the zddp additve is important, the shell rotella has a lot from what i heard but is getting changed, so I emailed the valvoline tech place about their street/race oil VR1 for its ZDDP content

they said it has 1200 ppm in each bottle, which is the same as the rotella.

Its sold in 10w-30 and 20w50. Is there any advantage in a performance engine to a thicker oil?

[silicon212]

Thicker oil is harder to pump than thinner oil, so unless you live in a hot climate, the 10w30 will rob your engine of less power.

[capriceowns]

Originally Posted by silicon212

Thicker oil is harder to pump than thinner oil, so unless you live in a hot climate, the 10w30 will rob your engine of less power.

so 10w-30 is not good in hot climates? i thought it was the other way around

[silicon212]

Heavier oil will hold up a little better in high temp extreme use.

[hotrod_chevyz]

If you run 10w30, by the time your due for an oil change the 10w30 is broken down to the point where you might as well not have any oil in it at all. Depending on the motor, some motors you cant run 20w50 because they have crap for oil circulation.

I wouldnt own a motor that "cant" run on 20w50.

[Blue Bowtie]

Contrary to what the number might indicate, SAE 20W oil is not twice as viscous as SAE 10W oil. 10W has a Kinematic viscosity of 32 S, while 20W has a Kinematic viscosity of 46 S. That's only one of the significant flaws of the antiquated SAE lubricant viscosity rating system. For example, as you may or may not be aware that 75W gear oil has the SAME viscosity as 10W engine oil. The difference between 75W and 80W gear oil might not sound like a lot due to the misleading SAE numbering, but 80W gear oil has over TWICE the viscosity of 75W gear oil (32 vs. 68). And 85W gear oil has almost FIVE TIMES the viscosity of 75W gear oil (32 vs. 150).

10W30 uses 10W oil as its base stock, and has a base oil Kinematic viscosity of 32. It requires polymer fortifiers to achieve stability of 68 basis points over its expected operating temperature range (32-100 S). 20W50 uses 20W oil as its base stock, and has a base oil Kinematic viscosity of 46. It requires polymer fortifiers to achieve stability of 174 basis points over its expected operating temperature range (46-220 S), or nearly three times as much fortifier.

As we know, thermoelastic polymer fortifiers can seem like they are helpful until they start to break down, and they are usually the first thing to break down in a lubricating oil. They are typically responsible for the majority of sludge formation in an engine, and having three times as much polymer in the oil can result in three times as much sludge by the time you are ready for a change.

If it were my engine, I'd find a PAO synthetic in the appropriate viscosity with zinc/phosphate EP additive and call it done.

[Blue Bowtie]

What's confusing me is that you have an '87 Caprice, but somehow it ended up with a flat tappet cam. AFAIK, all SBC passenger car engines switched to roller cams in the 1987 model year. 1986 was the last year for the flat tappet in all but trucks (and the first year for the 1-piece RMS).

Did you change the cam or engine?

[capriceowns]

Originally Posted by Blue Bowtie

What's confusing me is that you have an '87 Caprice, but somehow it ended up with a flat tappet cam. AFAIK, all SBC passenger car engines switched to roller cams in the 1987 model year. 1986 was the last year for the flat tappet in all but trucks (and the first year for the 1-piece RMS).

Did you change the cam or engine?

I have a different engine now. Its a 1981 350 that im building. Im kinda wishing it was a roller now...

the one problem I have with synethic is I cant afford all the racing ones that have the right ZDDP there all 11$ a quart and up

But what your saying BB if i find a synthetic oil in the 10w-30 that I can use go for it? otherwise go with regular 10w-30?

[silicon212]

Run the Rotella-T oil. It still has the proper ZDDP additive levels and actually costs less than regular oil.

[maxwedge]

Seconded on Rotella or true racing oil of some brand. Both have the old formula of zinc and phosphate additives, or the expensive synthetics. Used Quaker State racing then Amsoil racing in the pictured race car for 25 years, 7,200 rpm 525 hp engine, no bearing or cam issues during seasonal tear downs.

[Blue Bowtie]

Standard Oil Delo, Mobil Delvac, and Shell Rotella are some of the oils which still contain over 1,000 ppm zinc and phosphor. Another option is to add a bottle of GM EOS oil additive or Comp Cams #159 Additive at every oil change.

[capriceowns]

Originally Posted by Blue Bowtie

Standard Oil Delo, Mobil Delvac, and Shell Rotella are some of the oils which still contain over 1,000 ppm zinc and phosphor. Another option is to add a bottle of GM EOS oil additive or Comp Cams #159 Additive at every oil change.

is that safe to do, add a additive every oil change? I have 6quarts total for my engine filter is included in that.

[silicon212]

Yes, it is totally safe. Add a can of EOS to every oil change.

[capriceowns]

Originally Posted by silicon212

Yes, it is totally safe. Add a can of EOS to every oil change.

the GM EOS comes in 16 oz bottles only is that what your talking about? not the lifter prelube in a little 4 oz container.

[silicon212]

Correct. As BB said, the Comp Cams stuff works well as well. I believe that comes in 4-oz bottles, but I've never used it for that. I run Rotella, myself.