I also work for an oil major and have an active pension - called a RAP (retirement accumulation plan) from my employer. Yours may be similar, but it is useful to understand the mechanics of your plan.
In my case, the RAP plan is a cash balance plan, which is different from a defined benefit plan. I had a couple small pensions with previous employers (also oil majors) which were defined benefit plans. You should find out which type your pension is - defined benefit or cash balance.
While employed and before payout begins, the different plan types change in different ways with changes in interest rates. The basic difference is that a cash balance plan has a cash balance (duh) that is used to buy an annuity at whatever rates prevail when the annuity payout is selected. A defined benefit plan has a benefit that is defined (duh) and it doesn't change with prevailing interest rates. The big difference is what happens to your lump sum or annuity payment when interest rates change. Generally, rising rates are good for a cash balance plan because rising rates will increase the annuity payouts when/if you decide to annuitize. Falling rates are good for a defined benefit plan because they cause the lump sum option calculation to increase.
My employer's RAP is managed by Fidelity. My RAP (cash balance plan) grows at the 30 year treasury rate or 5%, whichever is higher. My employer puts a percentage of my monthly salary into the plan, the percentage is based on my age+years of service. It is employer only funded and entirely separate from the 401K. In my previous employer's defined benefit plans, you received a percentage for each year of service of the best continuous 36 months of earnings you had.
When I retire in the next few years my intention is to let my RAP continue to grow until I take SS, either at full retirement age or at age 70. My RAP has what I consider very good return rates (greater of 30 year treasury or 5 %) and I also think that rates will continue to rise, which is good for the eventual annuity calculations. I intend now to take my RAP eventually as an annuity rather than a lump sum, but it is available as a lump sum to my heirs until I annuitize it. In the intervening years I will consider the cash balance part of my portfolio bond allocation.
You can see how it takes an understanding of the mechanics of your particular pension to choose the best options for your situation. Pensions can be quite different in how they work.
I also wouldn't count on the pension staying active for the next 15 years. Oil majors are some of the last employers in the private sector to have active pension plans, but even a couple of them have frozen their plans in the last few years. My employer recently changed the pension rules for new hires, but they didn't totally freeze them out or alter the plan for grandfathered employees. Private sector pensions are a dying breed.