Best oil for 75 Z1?

I need to change the oil in my bike before I run it any more. What brand and weight would be the best? Does it have a filter anywhere?

The oil filter is accessed underneath the engine. Look for a round plate with a bolt in the middle of it. On my '75 Z1, I have to remove the Kerker 4-1 header to be able to take drop the filter.

Oil, I dunno. Whatever the manual says, I guess.

I personally use Castrol 10w40 but I believe the factory calls for 10w30 SAE oil. Some will say only use oil specifically designed for motorcycles because they contain special shear ingredients for use in motors that use same oil for engine and transmissions(transmission gears have tendency to tear oil molecules apart)but they sell for around $7+ a quart. I used to use Pennzoil but Castrol is my choice now. I know some guys use 10w30...10w40...and even 20w50 but although 20w50 is heavy and can stand abuse, it may be harder to use in cooler climates. I would think any 10w30 or 10w40 will be just fine. Synthetic oil is still touch and go. I have heard some guys say it's just fine and others have said it makes the bike smoke and lets the clutch slip because it is so slick.

"what's the best oil?" is right up there with "what's the best beer?" (Sam Adams)
Lots of opinions.
My opinion, for what it's worth is that the best oil is the kind that gets changed regularly. Castrol GTX 10W-40 in the winter, and 20W-50 in the summer. Two oil changes a year is probably excessive, especially for the miles I ride every year. But it's easy to change, and not that expensive.

Another vote for the Castrol GTX. Works fine for me...

Most of the race and high performance guys running tricked out Z1's and KZ's in my area use Valvoline Racing VR1 20W-50 oil. Part # VV211. Works great for the older engines.

Zippy

Thanks for all the replies. I appreciate the info.

Here we go again ,
They came over on the boat with FISH OIL in them .
The kind they used to pack tuna in .
No Kidding !!!
Any name brand 10/40 is great......with a new filter .
A mag plug sure wont hurt .

Just pick what is easy to get where you are and stick with it .

If you use a 20/50 make sure it HOT outside and you warm it up well before you jump on it .

Remember all those little rollers down in the bottom.

This is one of those questions if asked to 10 differnt people you will get 10 different answers.I have used Castrol 20w50 exclusively in bikes for over 30 years and never had an oil related problem.BUT 20-50 is a little stiff if you live in a colder climate.

Please take no offense, but by your question regarding the oil filter it sounds like you don't own a shop manual. I would strongly suggest you pick one up so you don't overlook other maintenance items that you can (and should) perform. These are nice bikes and keeping up with the maintenance helps them run their best. Good luck. Ed

Shell Rotella 15w-40. It's inexpensive and has all the good additives that these engines need. Even when changed twice as often as 4-stroke motorcycle oil you will save money compared to the more expensive (and no better) bike oils.

I do carry a quart of VR-1 racing oil to top off in case I can't find Rotella in the smaller bottles.