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15-50 instead of 20-50

18K views 41 replies 18 participants last post by  Lars Ferox 
#1 ·
most oils today do not contain Zinc because it can harm catalytic converters. I work for NAPA and they have Mobil 1 on sale . I noticed on the bottle that their 15-50 has Zinc added. Zinc is good for friction in places like push rods, valve stem tips etc. So i bought 4 Qts. Most of my rides are less than 10 miles so i doubt the lower viscosity # will harm anything.
only a few oils today have Zinc added. Many hi performance engines with flat tappet cams have had cam failure without Zinc.I know HD uses roller tappet cams but i still like the Zinc additive if i can get it.
Your thoughts on 15-50 being OK. This oil is considered a racing oil and i figure it does not have all the long life additives normal oil has but i change my oil often even with Synthetic.
 
#2 ·
Me personally..
I really dont care if oil is "on sale"
I stick with what's recommend...
If it ain't broke..
Don't fix it!
 
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#6 ·
well folks Mobil 1 is not exactly bargain basement oil. I normally use Mobil 1 20-50 anyway. i would never use a low quality oil just because it is on sale. Using motorcycle specific oil in a twin cam is fine but not necessary. Most motorcycle oil is formulated for wet clutches and transmissions. My twin cam has nether.
My question was about 15-50 & Zinc additives.
I do respect the opinions
THANKS
 
#15 ·
i use moblile 1 15-50 car oil, full synsthetic, from walmart. i add 1pt of stp oil additive, zddp( zinc and phosphorus) in every engine oil change. the zinc is a must for the valve trane
in any flat lifter camshaft engine. easy peazy. no better care for your harley engine at any price.:smile
 
#7 ·
I ride a twin cam ..
So,
I stick to what's recommended..
I'm not sure about using anything with an additive such as zinc..
Don't really see a benefit. It may just do more harm over time than good..
I look at it like.stp..zmax..or any other of that crap on the market.:eek-surprise

It's best IMO to stick with what works!
 
#9 ·
Here's info I got off the Mobil website (MSDS).

15-50 = .0012% phos .0013% zinc Phos. Is ZDDP
V twin= .0016% phos. .0017% zinc
------------------------------------------
Diff = - .0004%Diff -.0004%

Virtually identical zinc and phos. content. I use VTwin 20/50 only because it's on sale for the same price as 15/50 in my area.
 
#17 ·
About 4 years ago my friend rebuilt a 454 engine in a boat. He has done many. but he did not know Castrol GTX that you get today will not protect a new flat tappet cam with high valve spring tension. He lubed the lobes with break in paste,primed the oil system and it started right up. he did not let it idle and the comp cams destroyed itself pronto. Comp cams told him to use special oil now always.not just break in.
 
#24 ·
I'm into old cars and know MANY fresh rebuilt motors ruined during break in for this exact reason.

Wrong, your TC has both a wet clutch and trans. Also if your bike has cats you wouldn't want zinc going through them.
BUT it's your bike so do what ya want.
And this my friend is why the powers to be eliminated ZDDP from oil, they have to warranty emissions.
There is a whole industry dedicated to formulating oils so the old motors won't self destruct.
 
#28 ·
holy crap!!!!! my appologies to dan89, kainem and all my brothers on the harley davidson forum. this is no excuse but i read an article about substituting chevy lifters and did not realize they were comparing chevy roller lifters. i have had many engines apart(thirthy five years as owner of auto parts store and machine shop and job machine shop. but i confess i havent had a harley engine apart yet. only had two harleys and havent worn one out yet. thanks to you dan89 and kainem for straightening me out. crow pie for me! i shall wear the azzhat while eating it. i will use the zddp in my 88chevy truck and maybe take a swigg to get the stupid taste out of my mouth. please disregard the posts of mine that mentioned flat tappet lifters and zddp. i do have to thank guys for putting me in the dunce corner cause im so happy to now know my twin cam has roller lifters, cool!!!!!:smile sorry bobf i almost forgot to thank you too. the harley aint that old but i am also fat ugly and now i have egg on my face. i think i need a shower.
 
#34 ·
Agreed Schmidty, but rollers have less friction and resistance, plus don't disperse metal debris in to the engine during their normal wear.

Flat tappets also require valve adjustments as they wear and become concave in the centers, increasing lash.

Roller tappets also allow for use in a higher peak and cam curve, unlike flat tappets due to less friction and cam/tappet face mating. That less friction makes more horsepower.

Flat tappets can't be reused where rollers can, when changing a cam. They're not cam-specific regarding wear patterns.
 
#40 ·
My last race engine project was a ford stroker 351 windsor [ 377 in ]. It had a solid flat tappet cam with .610 lift. I had to break the cam in with only the outer valve springs installed. After 20 minutes i installed the inner springs also. That is how most do it with over 200 lbs seat pressure and a flat tappet cam.
 
#41 ·
Mobile 1 15/50 is a fine oil, most people dont use what is recommended anyway which is Harley oil or Diesel oil in the newer Rushmore bikes.
Almost all motorcycle oils do not meet that more stringent commercial classification.

Except me, I use 15/50 Commercially rated diesel oil which Harley requires CH4 to CJ4, Mystik JT8 semi syn. meets that, $64.00 delivered to my house for FOUR gallons. (not a mis print) or 2 gallon container for $35.00
Love the oil, posted many UOAs and a VOA on BITOG. Bikes runs sweet on it.

Amsoil also makes one, a 20/50 diesel oil which also mentions the motorcycle classification.
 
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