Do I need another objective?

[zzffnn]

Harry, good modern microscopy immersion oil does not dry. If yours seems too thick, then it might have the type B (thick) formulation. You can buy a vial of Cargille type A oil to try. The thinner type A oil should reduce the pressure of 100x NA 1.4 objective on cover slips.

[Free2Fish]

Thanks zzffnn, I’ll order some and give it a try.
The oil I have is Harleco Immersion Oil and it’s designated as “High Viscosity - 1250 centistokes so that may be the issue.

Harry