01 / The challenge
An offshore oil change did not fit the available window.
Oil analysis on SOLAR gas turbines at a North Sea platform identified elevated varnish potential. The maintenance team faced the prospect of deposits affecting bearings and control components while time and budget for replacing the turbine oil were constrained.
The offshore setting added work to any oil-change decision. Delivering replacement lubricant and removing the used charge required logistics as well as a suitable maintenance window. The operator needed a way to address the oil-system condition while keeping the turbines running.
The chosen response was to treat the existing oil and track its condition. Membrane patch colorimetry, or MPC, measures the colour of material collected on a test membrane to assess varnish potential. Repeated results would show whether the improvement held after treatment.
02 / The approach
Treat in service, then follow the oil over time.
Apply a qualified deposit treatment
A&S International recommended Fluitec DECON™ for turbine oil varnish removal, at a 5% concentration for these systems. The treatment circulated through the equipment while it remained in operation, with no oil drain or flush.
Use the existing filtration
The treatment mobilised deposits and varnish precursors into the circulating oil. The case describes the existing filtration removing mobilised material while the turbines continued operating.
Continue quarterly checks
The operator followed MPC results through ongoing quarterly oil analysis. That follow-up supported the decision to retain the oil and formally approve DECON™ for continued use across the platform’s turbine fleet.
03 / The documented outcome
MPC settled at 5 and the existing oil stayed in service.
MPC reduced to 5 following treatment and remained low and stable on the reported quarterly tests. The turbines continued operating without an oil change or production downtime during treatment.
The operator completed its formal management-of-change process, the internal review used to approve an operating change. DECON™ became an authorised ongoing treatment for the platform’s turbines, with wider use across that fleet planned.
Quarterly testing continued after the initial treatment, allowing the operator to follow whether the low varnish-potential result held during continued service.
- Varnish potential
- MPC reduced to 5
- Follow-up
- Low and stable on quarterly analysis
- Oil replacement
- No oil change required in the reported period
- Operating approval
- Continued treatment approved; fleet rollout planned
04 / Applying the findings
Make continued oil use a monitored decision.
For another turbine, start with the oil history, equipment requirements and the full analysis trend. Establish which properties need attention and whether the lubricant remains suitable for treatment. MPC testing addresses varnish potential; the wider oil assessment supports the decision to keep using the charge.
Build the follow-up into the treatment plan. Record the starting condition, lubricant compatibility review, sampling schedule and the operating response expected from the turbine. Set the acceptance criteria for that system and make responsibility for continued monitoring clear.
This case is useful where access and maintenance windows make an oil change difficult. It shows how treatment, repeat testing and the operator’s approval process can support continued oil use. The offshore compressor case follows another operating response: falling bearing temperatures and trips stopping within hours.