LONDON, April 29 (Reuters) - U.S. WTI crude differentials weakened on Tuesday as buyers again stayed on the sidelines, while North Sea loading programmes showed a drop in June supply.

JUNE PROGRAMS

* North Sea daily oil output in June is set to fall by nearly 14% compared with May, according to Reuters calculations based on loading programs provided by trade sources.

* The drop will mainly be driven by a sharp fall in Ekofisk loadings, which are pencilled in at just one cargo in June.

GRANGEMOUTH REFINERY

* Scotland's only oil refinery ceased crude oil processing as of Tuesday, operator Petroineos said, as the site transitions to an import terminal.

* The Grangemouth refinery mainly processed crude from the North Sea, to which it is connected via the Forties pipeline.

PLATTS WINDOW

* Indications are on a free-on-board (FOB) basis unless marked as cost, insurance and freight $(CIF)$ or delivered at place (DAP).

* Gunvor, Chevron, Exxon and Aramco offered cargoes in the window, a trade source said.

* WTI Midland: Exxon offered May 15-19 at dated Brent plus +1.00 CIF Rotterdam, down 40 cents from an offer on Monday.

* That is equal to roughly dated Brent minus 12 cents on an FOB basis according to Reuters calculations, down from plus 29 cents on Monday.

(Reporting by Alex Lawler; Editing by Sahal Muhammed)

((alex.lawler@thomsonreuters.com; Twitter/X: @AlexLawler100))

NORTH SEA CRUDE OIL DIFFERENTIALS AND OUTRIGHT PRICES: 
                    0#BFO-DIF     0#C-E 
Dated BFO       BFO- 
Brent           BFO-BRT       BFO-E 
Forties         BFO-FOT       FOT-E 
Oseberg         BFO-OSE       OSE-E 
Ekofisk         BFO-EKO       EKO-E 
 Monthly North Sea crude loading programmes     O/LOAD 
 OPEC OPEC                NSEA  North Sea 
 CRU  crude oil           PROD  oil products 
 DRV  derivatives         PRO/E European products 
  OILOIL  NYMOIL, IPEOIL, OILSPD, OILARB 
CRDWLDPRODEUR, PRODUS, APROD 
ENERGY energy speed guide   CRUDE/1 crude speed guide