Oil type / brand

[RobH]

I have a 2013 Z3. Any ideas what is a good oil to use? I used a quart of West Marine 15W40 (to keep it full during break in), but have been told Rotella 15W40 works fine too?

Thoughts?

[IDBoating]

Yep, Rotella 15W-40 is the answer. Remember to prefill your oil filter before installing it (presuming you have the remote filter option and the filter hangs downward). This will ease the shock load on your oil pump when you do oil/filter changes.

[TeamAllen]

You should be able to get Shell Rotella at Walmart for $13 a gallon.

[RobH]

Thanks guys. Will do.

[IDBoating]

Update: I should have said Rotella T. The "T" is important. There are several varieties of Rotella motor oil and you definitely want the "T" version.

[chpthril]

Pre-fiilling the filter avoids that 10 seconds of 0 oil pressure.

Brand: Pick one, there all about the same. Theres only a handful of refineries that bottle and label for everyone. There may be some slight differences from one formula to the next, but this is mainly for marketing. The key is to go with one that meets or exceeds the manufactures recommended API code.

Weight: This is where the most thought needs to be put. Im a huge fan of multi-vis oils, especially when the boat will be used from early spring to late fall when the temps are lower then peak summer. This helps to get that oil circulated upon initial start up.

Conventional v's synthetic: Personally, I have yet to see the engine wear in an engine running conventional oil, that synthetic is supposed to prevent. Regular maintenance is true key here. To take it a step further, Dom @ Forts has done a ton of research on using Syn in boats and other non-daily drivers. His experience has been that syn does not stay in place as long as conventional, when an engine sits unused. This leads to a dry start. I also dont buy into the extended intervals with syn. When we do an oil change, its not "warn out oil" we are draining, its all the combustion contaminants, moisture and dirt that we are taking out. Regardless of which type of oil you use, if its doing its job, it needs to be changed. Also, oil really doesnt wear out, but rather the additives in the oil get used up and are no longer effective. Many of the same additives are in both types.

Marine v's automotive oil: Marine blended has its advantages, so its worth using in my opinion. But, for a fresh water trailer boat thats serviced regularly, I have no issue at all using automotive grade oil.

[IDBoating]

Pre-fiilling the filter avoids that 10 seconds of 0 oil pressure.

I was taught that the reason for pre-filling the oil was to ease the shock load on the oil pump. When the engine first starts after a filter change, there is no backpressure as the filter fills up - and then suddenly there is a huge increase in backpressure when the filter tops off. Such sudden and large magnitude shocks are not good for pumps, and this one can be easily avoided by prefilling the filter if its mounting style permits it.

[chpthril]

I was taught that the reason for pre-filling the oil was to ease the shock load on the oil pump. When the engine first starts after a filter change, there is no backpressure as the filter fills up - and then suddenly there is a huge increase in backpressure when the filter tops off. Such sudden and large magnitude shocks are not good for pumps, and this one can be easily avoided by prefilling the filter if its mounting style permits it.

The filter, be it empty or pre-filled, is downstream of the pump. The oil pressure is actually resistance to flow, created by the tolerance of the oil passages.

[IDBoating]

The filter, be it empty or pre-filled, is downstream of the pump.

Yes. Agreed. That's why the output of the pump sees essentially no resistance while the filter is filling - because the filter is downstream. Then, all of a sudden, the filter is full and the pump instantly goes from wide-open-flow to the restricted flow you mentioned. Sudden, dramatic changes in backpressure like that are hard on hydraulic systems regardless of the working fluid in question. A classic example is "water hammer" in house water systems, which you can hear when a spigot is suddenly slammed closed or almost closed. The shock wave that travels through the system can damage system components.

In case anyone cares about the technical details: Why does the shock wave occur? It's because of a sudden impedence change. The fluid in question is moving at some speed - in this case "wide open" because there is essentially no resistance while filling an empty oil filter. Then suddenly, the filter tops off - and the flow rate must drop from "wide open" to "normal" almost instantaneously. So now we have the oil between the output of the pump and the input to the filter still moving at the "wide open" speed, but the input to the filter is "blocked" because it's full of oil. This is basically the same as slamming off a water spigot. The moving fluid cannot continue to flow at the same speed - in the spigot's case because it's been turned off, and in the filter's case because it's now full. In Engineering we refer to this as a change in impedance... the impediment to the flow was first one value, then changed to another. The speed of the change is important, and in this case it changes almost instantly. The result is a shock wave that starts where the impedance change occurred (the now-filled oil filter) and propagates back toward the oil pump.

That's why the shock wave occurs. To learn how damaging hydraulic shock can be, look up "water hammer". It's easy and totally free to prevent it in your engine's oil system: Just prefill the oil filter. Or don't. Your choice!

[TeamAllen]

Is there a down side to pre filling the oil filter? The only argument I have read basically worries that it allows unfiltered oil to go directly to the engine without being filtered first. I'm not saying I agree with that, just wondering? I would think since the oil is new it is pretty clean. Clean enough?

[chpthril]

Is there a down side to pre filling the oil filter? The only argument I have read basically worries that it allows unfiltered oil to go directly to the engine without being filtered first. I'm not saying I agree with that, just wondering? I would think since the oil is new it is pretty clean. Clean enough?

Oil flow typically comes from the pump into the center of the filter, through the filter material and exits the 6-8 holes around the threaded center. So if the oil is new, clean and is poured into the center of the filter, it will be filtered.

[bsmithuw]

Any tricks to installing the filled filter without spilling oil everywhere? I have the remote filter....

[chpthril]

Any tricks to installing the filled filter without spilling oil everywhere? I have the remote filter....

If the filter housing is such that filter mounts straight up and down, then just screw it on. But the trick is to not fill the filter completely full

[bsmithuw]

Even with the threads on bottom I should still fill it?

[chpthril]

Even with the threads on bottom I should still fill it?

If the filter mounts upside down, no point in filling, it will run out when you tip it over to mount it. Disable the ignition and crank it over in 10 second intervals till you see some pressure on the gauge. This fill the filter and gets oil where it needed to be before the engine sees running RPM's