Transit checklist you ask? What transit checklist? This was deleted in 2015 and most of the information was moved to the operating manual. I say most because they failed to move the requirement to check the oil filter differential pressure indicator at least once every 14 days. There is now no published requirement to check these DPIs. In fact, Rolls-Royce says you don't need to, more about that here. So read the current AOM text below for current guidance and take a look at the deleted guidance for some background.
The bottom line is this: If your next flight is longer than 7 hours you shouldn't be adding oil to both engines at the same time unless you are prepared to do an engine run. Most of these engines do exceed the 1/2 pint per hour.
This procedure has been around since 2006 and as of December 2012, only one engine in the entire fleet has been fitted with the new Remote Oil Filler Valve. So chances are you should be following this procedure. The procedure is covered by the Rolls-Royce Remote Oil Filler Valve Bulletin of July 14, 2006. More information at G450 Systems / Powerplant Oil System.
What follows comes from the references shown below. Where I think it helpful, I've added my own comments in blue.
[G450 AOM, §09-02-20, ¶2. Note.]
This entire page was deleted in 2015.
Figure: Transit Check, from G450 Quick Reference Handbook pg. NF-5/6.
Gulfstream G450 Aircraft Operating Manual, Revision 39, March 10, 2015.
Gulfstream G450 Quick Reference Handbook, GAC-AC-G450-OPS-0003, Revision 34, 18 April 2013
Rolls-Royce Tay Series Propulsion System Service Bulletin TAY-79-1698, Publication Ref. Ser-TayAC, Jul.14/06
This comes from an internal memorandum at Rolls-Royce:
Regarding checking the DPIs, the G450 AOM Section 2A Production Aircraft Systems 2A-79-10 2. F. Oil Filter Assembly, states “If debris collects within the filter restricting oil flow through the filter, a pressure differential will be detected by the switch. If the pressure differential reaches approximately eighteen (18) psi, the switch will indicate to the EEC an impending blockage of the filter. At approximately thirty (30±3) psi differential the oil will bypass the filter and a mechanical “pop-up” indicator will activate signaling the bypass.”. When the EEC gets the 18 psi oil pressure differential signal, the EEC will generate an ENGINE MAINTENANCE, L-R amber CAS messages which would drive maintenance to check the fault codes and take the appropriate troubleshooting/maintenance actions thus negating the need for DPI check in the QRH Postflight check since it would be annunciated in the cockpit prior to the DPI popping up at a thirty (30±3) psi differential.
Even though the oil system is designed to give ample caution of a potential oil filter bypass, there is certainly no harm in checking the DPIs when servicing the oil. If one should happen to find a DPI “popped” which was not preceded by an amber ENGINE MAINTENANCE, L-R CAS message, they should contact their Gulfstream or Rolls-Royce representative for further guidance.
If you are following the procedures in the AFM and AOM, you will never be directed to check the DPI and it appears that abides by Rolls-Royce guidance. As a technique, we service the oil at the end of each flight day using the system in the aft equipment bay and then we verify the oil levels at the sight glass on each engine. As long as we are there, we verify the DPI is closed. Some would argue that if we spot the DPI popped we are grounded. So be it, it is an expensive engine and I like to take care of it. More about how to do that: G450 Systems / Powerplant / Oil Servicing.