I have a 03 sportster 1200. I changed out the engine oil with mobil 15w 50 car oil. I need to change the primary out. I have some mobile 15w 50 left and I also have a quart of mobile 75w 90 gear oil.

Will either work or do I need to go to to my local independent guy for what is right? I hate to waste anything but I dont want to screw up either. I detest HD dealers and refuse to give them a nickle for anything.. I appreciate any help here. Thanks.

 

Try either one. But next time get the Mobil1Vtwin 20w50 from Autozone. It is speced for both engine & primary on your bike. It is a bit more $$ at $10/qt but you don't have to worry about the wet clutch application. Castrol Power 4T 20w50 from Advanced Auto will work as well.

 

I'd take the car crap out and replace it with mobil 1 20/50 v-twin for the eng/primary and the mobil 1 75/90 in the tranny.

 

I am going to put the 75 90 in it and go with it. Im still not sold on the marketing gimmick of Motorcycle specific oils.

PS" I love that Triumph Tbird. That is one hot ride.

 

Thanks for your opinion. That car crap is going to stay in it for a while because I have six more quarts of red cap mobil 15 50. The HD dealer told me to never ever run synthetic when I bought it and I just busted out laughing. They said it was too slick and just a bit later they were begging me to buy syn 3 by HUgo Citgo but that was ok. Its all about marketing. Didnt and wont work on me.

My main concern at this minute is the primary and I have some mobile 1 75 90 for that so thanks for your opinion.

 

For someone with so few posts you have some pretty strong views! Open your mind and be more receptive to good advice.

Air-cooled engines place different demands on their oils than water-cooled ones and cars, hence we get offered oils blended to suit them. Cars don't run their clutch in engine or trans oil and that is another reason why we get different oils, as KBFXDLI told you.

It is not wise to use synthetic oil in a new engine, so it is normal to run the bike on normal oils during the running in period, which probably explains what your dealer told you.

 

GRBrown - if it ain't wise to use synthetic in a new engine why do some new cars and certain motorcycles, including HDs, come with an initial fill of synthetic?

The following ain't necessarily aimed at you, nor anyone specifically -

As far as the car vs mc-specific stuff, far too many have used plain ol' car oil for far too long to know that there is little-to-no appreciable difference. Yes, there is some difference, but it seems to be no more than what is found even in moving from one mc-specific oil brand to another. The biggest differences seem to be in the additive packages, and even there a 15w-50 or similar weight car oil will typically have a very robust package that will often put some mc oils to shame.

These ain't my opinions. I have samples of all my oil tested, new and used. And practical experience includes over 100,000 miles on a '72 XLCH, over 200,000 miles on a '78 Shovel with one rebuild at 125,000 miles, and over 130,000 miles on a '87 Sloptail. The XLCH used straight 50 and 60 HD and then Castrol 20w-50 (car oil), Shovel had straight 50 weight HD oil initially, followed with Castrol 20w-50 for most of its time with me. I got the Sloptail with over 40,000 on it and have no idea what oil was used; it did still have over 90% of the cylinder wall cross-hatching left when I pulled the top off to replace the base gaskets. I used 20w-50 Havoline (car oil) and 15w-50 Mobil 1 (car oil) after that. At 130,000 miles a crack in the left case from the previous owner's use of a too-large sheet metal screw on the alternator wire clamp caused me to replace it with a '99 crate motor; there is still over 90% of the cross-hatching left in the '87 motor. The crate motor has had nothing but synthetic from day one; Mobil 1 15w-50 (car oil), and now some actual mc oil, Castrol 20w-50, that I got on sale at WalMart.

Old Sportsters had to use the same oil in the engine and primary/tranny as there was a transfer valve between the engine and primary. Older Big Twins used the same oil in the engines and primary as the oil pump fed the primary as well as the engine. Newer BTs have the primary isolated - HD finally did what most of us did with our bikes - seal the primary and use something better than the engine oil of the time.

Bottom line is as long as you use any quality oil of the correct viscosity for expected conditions, use a good filter, change both at least as often as the bike manufacturer or oil manufacturer requires, you're going to do just fine. And I prefer to use gear oil in the transmission rather than an engine oil; an oil designed to allow its use in both will have to have some compromises. Last caveat would be to be careful with what is in the primary; some say that certain oils cause a clutch to slip. However, all the times I have had someone actually present that argument there were mitigating problems that made it impossible to confirm. Seems the problems were solved by clutch adjustment, or sometimes even replacing the worn out clutch.

My experience is with HDs; I care nothing about metrics and their shared sump design where oil choice can definitely cause certain problems.

Finally, the old bug of HD and their dealers saying to not use synthetic was based only on one thing - HD had not tested any synthetic oil in their bikes so they did not recommend its use. The dealers and their mechs took HD's statement a step too far and mumbled stuff about warranties, too slippery, etc. None of the warranty, slickery stuff was true (U.S. warranty; don't know how they do it across the pond), and once HD speced some synthetic, tested it to their satisfaction, they started selling it and recommending it. Shoot, back in the Ironhead & Shovehead days, HD only recommended their oil; there wasn't even a reference to using diesel spec oils.

To repeat - use a quality oil of the correct viscosity for your conditions, use a good filter, change at least as often as manufacturer requires. Do all that and brand name really doesn't matter, nor does the differences between normal and mc-specific.

 

The post above by POCOJC is the most accurate and intelligent oil statement I have read yet.

 

That is because he is from Ohio......

 

Right there it is in a nutshell. That should be required reading for entry to the oil sub-forum. I just did the 125,000 mile service on my 07 Ultra using Mobil1 15-50. That is what I have used 90% of the time in it. It did not use a drop between changes, although if I run the **** out of it will occasionally. For me, the proof is right out there in the garage.

Drink the Kool-aid if you want. I am gonna save my money for other things.