Should I Change The Oil On Rebuilt Engine??

[12guns]

Last spring we had the engine rebuilt on my friends 89' 7.4 Mercruiser. We broke it in as instructed and have no more than 5 or 6 hours on the engine. Does it need an oil change after the break in and few hours we put on it? The mechanic has a specific Amzoil w/ more zinc and additives in it, which should last a long time. I just wanted to see if an oil change was in order or if I might get by with a simple filter change. Thanks for any help! We plan to get on the lake this weekend, can't wait!

 

[emoney]

Re: Should I Change The Oil On Rebuilt Engine??

What's the mechanic's suggestion that did the rebuild? You can never change oil "too often", I do know that.

 

[90stingray]

Re: Should I Change The Oil On Rebuilt Engine??

http://cgi.ebay.com/ebaymotors/COMP...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Comp cams makes additive that i always use on new motors... you can change the oil but i would add the additive again. Then, the next oil change after that one, should be good to go as normal. Might be overkill, but makes me feel better. But like stated earlier... talk to your builder. He will prolly want you to buy some more high dollar oil

 

[dubs283]

Re: Should I Change The Oil On Rebuilt Engine??

most builders recommend 10 hours on a rebuild, then oil change

after that, normal intervals

 

[12guns]

Re: Should I Change The Oil On Rebuilt Engine??

Thanks for the quick replies. I tried to call him a time or two with no answer. 10 hours sounds about right to me. I'll go ahead w/ the filter change tomorrow, then change the oil later this spring/summer. And I will be sure to use the right oil. This engine has been messed with so much in the past, it's not all stock. The mechanic explained something about the crank shaft and type of lifters that made the additives more needed here than in other 454's. I'll find out more when I talk to him. Thanks guys!

 

[solar7647]

Re: Should I Change The Oil On Rebuilt Engine??

If the engine has a flat tappet cam the zinc additive is used to break in the cam and litters, they say that a flat tappet cam will ware out faster with today's oils because they have less to no zinc then they did back in the day. This is because the zinc causes issues with catalytic converters and today's engines have hydraulic roller litters so they don't need the zinc witch helps treat flat hydraulic litters. The science of it is once the lifter heat up they absorb zinc making them harder....at least thats what I read a lot about dealing with a similar issue last year when I rebuilt my 3.7l.

To answer your question, yes you need to change after break in because during the break in the oil removes all the assembly lube used when the engine was being built and it can gunk up and it contaminates the oil. You should how ever add a zinc additive or get an oil with higher zinc they are usually marked as having more zinc for flat tappet cams for every oil change.

 

[Art Bernard]

Re: Should I Change The Oil On Rebuilt Engine??

When in doubt, change the oil. It certainly wont hurt anything, and you'll feel more confident with fresh engine and foot oil instead of worrying about it. I change all fluids often and have never had a lubrication related problem.

Art

 

[12guns]

Re: Should I Change The Oil On Rebuilt Engine??

If the engine has a flat tappet cam the zinc additive is used to break in the cam and litters, they say that a flat tappet cam will ware out faster with today's oils because they have less to no zinc then they did back in the day. This is because the zinc causes issues with catalytic converters and today's engines have hydraulic roller litters so they don't need the zinc witch helps treat flat hydraulic litters. The science of it is once the lifter heat up they absorb zinc making them harder....at least thats what I read a lot about dealing with a similar issue last year when I rebuilt my 3.7l.

To answer your question, yes you need to change after break in because during the break in the oil removes all the assembly lube used when the engine was being built and it can gunk up and it contaminates the oil. You should how ever add a zinc additive or get an oil with higher zinc they are usually marked as having more zinc for flat tappet cams for every oil change.

You hit the nail on the head, I just couldn't remember what he had told me! Thanks so much for the replies. It probably doesn't have more than 5 or 6 hours on the rebuilt engine right now. I'll probably change the filter out tomorrow and change the oil after another 5 or so hours. Thanks again

 

[12guns]

Re: Should I Change The Oil On Rebuilt Engine??

If the engine has a flat tappet cam the zinc additive is used to break in the cam and litters, they say that a flat tappet cam will ware out faster with today's oils because they have less to no zinc then they did back in the day. This is because the zinc causes issues with catalytic converters and today's engines have hydraulic roller litters so they don't need the zinc witch helps treat flat hydraulic litters. The science of it is once the lifter heat up they absorb zinc making them harder....at least thats what I read a lot about dealing with a similar issue last year when I rebuilt my 3.7l. \

I'm about to change the oil, can you point me to a good weight with higher zinc? I'd like to run sythetic, should I still add the additional zinc? Thanks! I know there are tons of opinions about which oil, just looking for the right weight for hot summers in Arkansas. Boat won't be run at all in the winter. Thanks